Block 1 Exam 4 Part 2 Flashcards
What happens to anti-apoptotic proteins like BCL-2 and BCL-X_L as the T cell response declines?
Their levels drop, leading to increased cell death.
Which protein is activated due to growth factor deprivation and triggers apoptosis?
BH3-only protein BIM.
What role do phosphatases such as SHP-1 and SHP-2 play in T cell activation?
They dephosphorylate signaling substrates to limit the duration or magnitude of T cell activation.
What is the role of PD-1 in T cell regulation?
It restrains previously activated CD8+ T cells in peripheral tissues, limiting their activity.
How do regulatory T cells help in the decline of T cell responses?
By engaging CTLA-4 with B7 on APCs and suppressing effector T cell responses, thereby limiting immune responses and preventing autoimmunity and allergy.
What is the ultimate source of genetic variation?
Mutation
What is the probability that a parent will transmit a specific allele at a locus?
1/2, as each allele has an equal chance of being transmitted.
What is the multiplication rule in probability?
The probability of independent events happening together is the product of their individual probabilities.
What is the addition rule in probability?
The probability of either one outcome or another is the sum of their individual probabilities.
If a couple wants to know the probability that all three of their children will be girls, what is the answer?
1/2 _ 1/2 _ 1/2 = 1/8.
What is the probability of getting either two heads or two tails in two coin tosses?
1/4 + 1/4 = 1/2.
What is the probability that a couple planning three children will have all of the same sex (either all boys or all girls)?
1/8 + 1/8 = 1/4.
What does genotype frequency represent?
The proportion of each genotype in a population.
do you calculate the frequency of a genotype in a population?
Divide the number of individuals with that genotype by the total number of individuals in the population.
If 64 out of 200 people have the MM genotype, what is the frequency of MM?
0.32 (64/200)
What does gene frequency represent?
The proportion of each allele at a specific locus in a population.
How do you calculate the frequency of an allele in a population?
Divide the number of copies of the allele by the total number of alleles at that locus.
How do you calculate the frequency of allele M if there are 248 M alleles out of 400 total alleles?
0.62 (248/400).
What is the relationship between the sum of all genotype frequencies and the sum of all gene frequencies in a population?
Both sums must equal 1.
What does the Hardy-Weinberg principle describe?
The relationship between gene frequencies and genotype frequencies in a population under random mating conditions.
What are the allele frequencies labeled as in the Hardy-Weinberg principle?
p for allele A and q for allele a.
How do you calculate the frequency of the AA genotype using allele frequencies?
p_ (p multiplied by p).
How do you calculate the frequency of the aa genotype?
q_ (q multiplied by q).
What is the formula for the frequency of the heterozygote genotype (Aa)?
2pq.
In a population, if the frequency of allele A (p) is 0.7, what is the frequency of allele a (q)?
0.3 (since p + q = 1).
What does q_ represent in the context of recessive diseases?
The frequency of affected individuals (homozygotes aa) in the population.
If q_ for a recessive disease like cystic fibrosis is 1/2500, what is the value of q?
0.02 (q = Ã(1/2500)).
How do you estimate the frequency of heterozygous carriers (Aa) if q is 0.02?
2pq, which simplifies to 2q because p Å 1, so 2 _ 0.02 = 1/25.
Why are recessive disease alleles often hidden in populations?
Because they are commonly carried by heterozygotes (Aa) who do not show symptoms of the disease.
What is the source of all genetic variation?
Mutation
How does natural selection affect genetic variation?
It increases the frequency of favorable mutations and decreases the frequency of unfavorable ones.
What typically happens to disease-causing mutations in a population?
They are continually introduced through errors and removed by natural selection.
How can a disease mutation provide a selective advantage?
In certain environments, like areas with malaria, a mutation can provide survival benefits, as seen with sickle cell heterozygotes.
Why do sickle cell heterozygotes have an advantage in malaria-endemic regions?
The malaria parasite does not survive well in the erythrocytes of sickle cell heterozygotes, reducing their risk of dying from malaria.
What happens to the frequency of the sickle cell mutation in environments without malaria?
Natural selection acts against it, reducing its frequency.
Why does the sickle cell mutation persist at a high frequency in certain populations?
Because it provides a survival advantage in malaria-endemic regions, despite being harmful in homozygotes.
What does the example of sickle cell disease illustrate about genetic variation?
It shows how natural selection can cause variation in the incidence of genetic diseases among different populations based on environmental factors.
What is natural selection?
It is the process where alleles that provide survival or reproductive advantages increase in frequency, while those with disadvantages decrease.
How does natural selection affect skin pigmentation as humans moved to higher latitudes?
It increased the frequency of variants that adapted skin pigmentation to the new environments.
What is an example of natural selection related to lactase persistence?
In populations that began drinking cow’s milk through adulthood, natural selection increased the frequency of hereditary lactase persistence.
How has natural selection acted on populations living in high-altitude environments?
It has increased the frequency of adaptations in the hypoxia-inducing factor pathway, allowing survival in oxygen-deficient areas like the Tibetan plateau.
What is genetic drift?
A random evolutionary process that causes larger changes in gene frequencies in smaller populations.
What is the founder effect?
It is a special case of genetic drift where a small founder population experiences large changes in gene frequency due to its small size.
How did genetic drift affect the Old Order Amish population in Pennsylvania?
Genetic drift increased the frequency of Ellis-van Creveld syndrome among the Amish, a population founded by about 50 couples.
What is gene flow?
The exchange of genes between populations, which tends to make them genetically more similar over time.
What happens to sickle cell disease frequency in African Americans compared to African populations due to gene flow?
Gene flow between African Americans and European Americans decreased the frequency of sickle cell disease in African Americans.
What is mutation-selection balance?
It predicts a relatively constant gene frequency when new mutations introduce harmful alleles, while natural selection removes them.
Why are recessive disease-causing alleles generally more common than dominant ones?
Because recessive alleles are often hidden in heterozygotes, protecting them from natural selection.
What does the selection coefficient (s) represent?
It represents the reduction in offspring for those carrying a specific allele, used to predict gene frequency in mutation-selection balance.
What is non-Mendelian inheritance?
It refers to patterns of inheritance that do not follow Gregor Mendel’s principles, including sex-linked mutations, mitochondrial inheritance, anticipation, and imprinting.
What are sex-linked mutations?
Mutations that occur on the sex chromosomes (X and Y). Diseases caused by these mutations are referred to as X-linked or Y-linked.
What is significant about the X chromosome in relation to disease?
The X chromosome is large (155 Mb) and contains nearly 1300 genes, many of which are associated with X-linked diseases.
How does the Y chromosome compare to the X chromosome?
The Y chromosome is much smaller (60 Mb) and contains only a few dozen genes.
What is mitochondrial inheritance?
It refers to the inheritance of the mitochondrial genome, which is passed down only from the mother.
Why do mitochondrial diseases have a unique pattern of inheritance?
Because the mitochondrial genome is inherited exclusively from the mother, mitochondrial diseases show a maternal inheritance pattern.
What is anticipation in genetics?
Anticipation is the phenomenon where some genetic diseases manifest at an earlier age in more recent generations of a family.
What is genetic imprinting?
Imprinting is when certain genes are expressed only from the chromosome inherited from one parent, either maternal or paternal.
What is X inactivation?
It is the process by which one of the two X chromosomes in each somatic cell of a female is randomly inactivated to achieve dosage compensation.
Why is X inactivation necessary?
To equalize the amount of X-linked gene products between males (who have one X chromosome) and females (who have two X chromosomes).
When does X inactivation occur?
Early in female embryonic development.
How is the X chromosome chosen for inactivation?
The X chromosome to be inactivated is chosen randomly in each cell, resulting in roughly half of the cells having the maternal X chromosome active and the other half having the paternal X chromosome active.
What happens to the X chromosome after it is inactivated?
It remains inactive in all descendants of that cell.
Why are females considered mosaics in terms of X chromosome activity?
Because they have two populations of cells, one with an active maternal X chromosome and the other with an active paternal X chromosome.
Are males mosaics for the X chromosome?
No, males are hemizygous for the X chromosome, meaning they have only one X chromosome and do not undergo X inactivation.
What are sex-linked genes?
Genes located on either the X or the Y chromosome.
Why are X-linked diseases more common than Y-linked diseases?
The X chromosome is larger and contains more genes compared to the Y chromosome.
Why are X-linked recessive diseases more common in males than females?
Males have only one X chromosome, so if they inherit the disease-causing allele, they will express the disease.
Can X-linked recessive diseases be passed from father to son?
No, fathers pass their Y chromosome to sons, not the X chromosome.
How can X-linked recessive diseases appear to skip generations?
The disease can be passed through phenotypically normal heterozygous females (carriers), who may pass it on to their sons.
What is a manifesting heterozygote?
A female carrier of an X-linked recessive disease who shows mild symptoms due to random X inactivation favoring the diseased allele.
Why might a female with Turner syndrome be affected by an X-linked recessive disease?
Because she has only one X chromosome, any recessive disease allele on that chromosome will be expressed.
What is the probability of a female being affected by an X-linked recessive disease?
It is much lower than in males because females need two copies of the recessive allele to express the disease.
What is an example of an X-linked dominant disease?
Hypophosphatemic rickets, which impairs the kidneys’ ability to reabsorb phosphate.
Why are X-linked dominant diseases less common than X-linked recessive diseases?
X-linked dominant diseases are generally fewer and often less prevalent due to their inheritance patterns.
Why are X-linked dominant diseases more common in females than in males?
Females have two X chromosomes, so they are about twice as likely to inherit the disease-causing gene.
Can X-linked dominant diseases be passed from father to son?
No, because fathers pass the Y chromosome to their sons, not the X chromosome.
What happens to males with X-linked dominant diseases that are lethal?
They often do not survive to term, as seen in disorders like incontinentia pigmenti type 1 and Rett syndrome.
What is a key feature of Rett syndrome?
It is a neurodevelopmental disorder characterized by autistic behavior, intellectual disability, seizures, and gait ataxia.
How does random X inactivation affect the severity of X-linked dominant diseases in females?
It can lead to milder symptoms if a larger percentage of X chromosomes with the disease mutation are inactivated.
How are Y-linked traits inherited?
They are passed strictly from father to son.
What is an example of a Y-linked trait?
The gene that initiates differentiation of the embryo into a male.
What is a sex-limited trait?
A trait that occurs only in one of the sexes, such as uterine defects in females or testicular defects in males.
What is a sex-influenced trait?
A trait that occurs in both sexes but is more common in one sex, like male-pattern baldness.
Is male-pattern baldness strictly X-linked?
No, it is influenced by both X-linked and autosomal genes, which explains father-to-son transmission.
What is mitochondrial DNA (mtDNA)?
It is a small, circular DNA molecule found in mitochondria that encodes rRNAs, tRNAs, and polypeptides involved in oxidative phosphorylation.
How is mtDNA inherited?
Exclusively through the maternal line, as only eggs contribute mitochondria to the developing embryo.
What is heteroplasmy?
It is the presence of a mixture of normal and mutated mtDNA within a cell, leading to variable expression of mitochondrial diseases.
Why do mitochondrial diseases often affect the central nervous system?
The central nervous system requires large amounts of ATP, making it highly vulnerable to mtDNA mutations that impair energy production.
What is Leber hereditary optic neuropathy (LHON)?
A mitochondrial disease caused by missense mutations in mtDNA that leads to rapid loss of central vision due to optic nerve death
What is the role of single-base mutations in mitochondrial diseases?
They can cause disorders like myoclonic epilepsy with ragged-red fibers (MERRF) and mitochondrial encephalomyopathy with stroke-like episodes (MELAS), both of which are heteroplasmic and highly variable in expression.
What types of mutations cause Kearns-Sayre disease and Pearson syndrome?
Duplications and deletions in mtDNA.
How common are mitochondrial diseases?
Approximately 1 in 4000 individuals is affected by a mitochondrial disease, with most cases due to mitochondrial mutations
Can mitochondrial mutations contribute to aging?
Yes, it is suggested that mtDNA mutations accumulating through life due to free radical formation could contribute to the aging process.
What is the significance of mitochondrial mutations in common diseases?
Mitochondrial mutations are linked to late-onset deafness, some cases of type 2 diabetes, and possibly Alzheimer’s disease.
What is genomic imprinting?
It is a process where the expression of an allele depends on whether it is inherited from the mother or the father, leading to gene silencing of one allele.
How does genomic imprinting affect gene expression?
One allele is transcriptionally inactive due to imprinting, resulting in only one active copy of the gene.
What are imprinted genes typically associated with?
Heavily methylated DNA and chromatin condensation that inhibit transcription.
What is Prader-Willi syndrome (PWS) and how is it caused?
PWS is a disorder caused by a deletion on chromosome 15 inherited from the father, affecting genes that are normally active only on the paternal chromosome.
What is Angelman syndrome (AS) and how is it caused?
AS is a disorder caused by a deletion on chromosome 15 inherited from the mother, affecting genes that are normally active only on the maternal chromosome.
What is the gene associated with Angelman syndrome?
UBE3A, which is active only on the maternal chromosome in brain tissue.
What is Beckwith-Wiedemann syndrome and how is it caused?
It is an overgrowth disorder caused by imprinting errors on chromosome 11, leading to overexpression of genes like IGF2 or loss of expression of growth-regulating genes.
How does uniparental disomy contribute to Beckwith-Wiedemann syndrome?
By inheriting two copies of the paternal chromosome 11 or losing imprinting on the maternal copy, leading to overexpression of IGF2.
What causes Silver-Russell syndrome?
A loss of methylation of DMR1 on chromosome 11p15.5, leading to underexpression of IGF2 and diminished growth.
What distinguishes Silver-Russell syndrome from Beckwith-Wiedemann syndrome in terms of IGF2 expression?
Beckwith-Wiedemann syndrome is caused by overexpression of IGF2, while Silver-Russell syndrome results from underexpression of IGF2.
What is humoral immunity mediated by?
B lymphocytes; secreted antibodies
What is the main function of humoral immunity?
Defense against extracellular microbes and microbial toxins.
What is the key difference between humoral immunity and cell-mediated immunity?
Humoral immunity uses antibodies, while cell-mediated immunity is mediated by T lymphocytes.
What types of microorganisms does humoral immunity primarily combat?
Extracellular bacteria, fungi, and viruses before they infect cells or after being released from infected cells.
What happens if there are defects in antibody production?
Increased susceptibility to infections by bacteria, fungi, and viruses.
How do most current vaccines provide protection?
By stimulating the production of antibodies.
In what harmful conditions can antibodies mediate tissue injury?
In allergies, autoimmune diseases, blood transfusion reactions, and transplant rejection.
What does antibody-mediated elimination of antigens involve?
Effector mechanisms involving phagocytes and complement proteins.
Where are antibodies produced?
Plasma cells in secondary lymphoid organs, inflamed tissues, and bone marrow.
What is the significance of antibodies being transported across the placenta?
They protect the developing fetus by entering the fetal circulation.
Where do long-lived plasma cells reside?
Mainly in the bone marrow.
Why are antibodies the primary defense mechanism in mucosal organs and the fetus?
T lymphocytes are not transported into mucosal secretions or across the placenta.
What region of immunoglobulin (Ig) molecules mediates many of the effector functions of antibodies?
The Fc region.
Which immunoglobulin isotypes activate the complement system?
IgM and some IgG subclasses (IgG1, IgG2 to a limited extent, IgG3).
What is the only antibody function mediated entirely by antigen binding?
Neutralization.
How is complement activation triggered by antibodies?
By binding to a multivalent antigen, clustering antibody molecules close together.
How do antibodies neutralize microbes and microbial toxins?
By blocking the binding of microbes and toxins to cellular receptors.
What is an example of a microbe that uses surface molecules to infect host cells?
Influenza virus uses hemagglutinin to infect respiratory epithelial cells.
How do antibodies prevent microbes from interacting with cellular receptors?
Through steric hindrance, preventing the microbes from binding to receptors.
How do microbial toxins like tetanus toxin and diphtheria toxin cause injury?
By binding to specific cellular receptors and interfering with normal cell functions.
How do antibodies protect against microbial toxins like tetanus and diphtheria?
By preventing toxins from binding to their target receptors and causing tissue injury.
What is the role of IgA antibodies in the lumen of the gut?
They agglutinate microbes, reducing infectivity and facilitating clearance by peristalsis.
What effect can antibodies have on microbes besides steric hindrance?
They can induce conformational changes in microbial surface molecules, preventing receptor interaction.
What are the two primary antibody isotypes involved in neutralization?
IgG in the blood and IgA at mucosal sites.
What makes antibodies most effective at neutralizing microbes?
High affinity for their antigens, produced by affinity maturation.
How do some microbes evade antibody-mediated neutralization?
By mutating the genes encoding their surface antigens.
How do IgG antibodies promote the phagocytosis of microbes?
By coating (opsonizing) the microbes and binding to Fc receptors on phagocytes.
What immune cells express Fc receptors that promote phagocytosis of opsonized particles?
Mononuclear phagocytes and neutrophils.
What is the function of the Fc_ receptors on phagocytes?
To bind IgG-coated particles and promote phagocytosis.
Which complement activation product can coat microbes to promote their phagocytosis?
C3b
What is the process of coating particles to promote phagocytosis called?
Opsonization
Which Fc_ receptor has the highest affinity for IgG antibodies?
Fc_RI (CD64).
Which immune cells express the high-affinity Fc_RI receptor?
Macrophages and neutrophils.
What is the function of the Fc_RIIB receptor?
It is an inhibitory receptor that regulates immune responses.
What happens when multiple Fc receptors are cross-linked by IgG-coated particles?
It leads to phagocyte activation and engulfment of the particles.
What are the primary microbicidal substances produced by activated phagocytes?
Reactive oxygen species, nitric oxide, and hydrolytic enzymes.
What is ADCC (Antibody-Dependent Cell-Mediated Cytotoxicity)?
Process where NK cells and other leukocytes destroy antibody-coated cells.
Which receptor do NK cells use in ADCC?
Fc_RIIIA (CD16).
What triggers NK cells to perform ADCC?
Antibody-coated target cells.
Why doesn’t ADCC occur with free IgG in the plasma?
Fc_RIII binds only to clustered IgG on cell surfaces, not to free IgG.
What do NK cells release during ADCC?
Cytokines like IFN-_ and granule contents to kill the target cells.
Can ADCC be mediated by other cells?
Yes, macrophages can also mediate ADCC.
What is the complement system?
A set of serum and cell surface proteins involved in eliminating microbes and complementing antibody function.
How does complement activation enhance immune response?
It focuses immune attack on microbial surfaces and amplifies the immune response through sequential proteolysis of proteins.
What are zymogens in the context of complement activation?
Inactivated proteins that gain proteolytic activity through sequential activation, leading to a proteolytic enzyme cascade.
How are complement proteins activated?
By binding to microbial surfaces, antibodies, and other antigens, leading to their stable activation.
What role do regulatory proteins play in complement activation?
They inhibit complement activation on normal host cells to prevent damage, while microbes lack these regulatory proteins and are susceptible to complement activation.
What are the three pathways of complement activation?
Classical, alternative, and lectin pathways.
What activates the classical pathway of complement activation?
IgM and IgG antibodies bound to antigens.
What activates the alternative pathway of complement activation?
Microbial cell surfaces in the absence of antibody.
What activates the lectin pathway of complement activation?
Plasma lectins binding to surface carbohydrates on microbes.
What is the central event in all complement activation pathways?
Proteolysis of the complement protein C3 to generate C3a and C3b.
What is the role of C3b in complement activation?
C3b covalently attaches to microbial surfaces or antibody-bound antigens and promotes phagocytosis.
What enzyme complex cleaves C5 into C5a and C5b?
The C5 convertase.
What are the functions of C5a and C5b in complement activation?
C5a stimulates inflammation, and C5b contributes to pore formation in microbial membranes.
What initiates the alternative pathway of complement activation?
The stable attachment of C3b to microbial surfaces without the need for antibodies.
What is C3 tickover?
The continuous low-rate hydrolysis and cleavage of C3 to generate C3b.
What causes C3b to become covalently attached to cell surfaces?
The exposure of the reactive thioester bond in C3b after cleavage.
What happens to C3b if it does not form covalent bonds with cell surfaces?
It remains in the fluid phase and is quickly hydrolyzed, becoming inactive.
What is the role of Factor B in the alternative pathway?
Factor B binds to C3b on cell surfaces and is cleaved by Factor D to form the alternative pathway C3 convertase.
What is the C3bBb complex?
The alternative pathway C3 convertase that cleaves more C3 molecules.
How does the alternative pathway C3 convertase amplify complement activation?
By forming a complex with C3b and Bb, which cleaves additional C3 molecules.
What role does properdin play in the alternative pathway?
Properdin binds to and stabilizes the C3bBb complex, especially on microbial surfaces.
What forms the alternative pathway C5 convertase?
A complex containing one Bb moiety and two molecules of C3b.
What initiates the classical pathway of complement activation?
Binding of C1 to the CH2 domain of IgG or the CH3 domain of IgM bound to antigen.
Which IgG subclasses are the most efficient at activating the classical pathway?
IgG1 and IgG3.
Why can only antibodies bound to antigens initiate classical pathway activation?
Because C1q needs to bind to at least two Ig heavy chains to be activated, which requires antibodies to be bound to antigens.
What role does C1q play in the classical pathway?
C1q binds to the Fc regions of IgG or IgM, initiating the activation of C1r and C1s.
How does C1s contribute to complement activation in the classical pathway?
C1s cleaves C4 into C4b and C4a, with C4b forming covalent bonds on the cell surface.
What is the function of the C4b2a complex?
It is the classical pathway C3 convertase that cleaves C3 into C3a and C3b.
How does the C3b generated by the classical pathway affect the complement system?
C3b can bind Factor B, generating more C3 convertase and amplifying complement activation.
What forms the classical pathway C5 convertase?
The C4b2a3b complex, which cleaves C5 and initiates the late steps of complement activation.
Why is IgM a more efficient complement-fixing antibody than IgG?
Because a single IgM molecule can bind multiple C1q molecules, while IgG requires multiple molecules to bind C1q.
What triggers the lectin pathway of complement activation?
Binding of microbial polysaccharides to circulating lectins such as mannose-binding lectin (MBL) or ficolins.
What are the key components of MBL and ficolins involved in the lectin pathway?
MBL has a collagen-like domain and a carbohydrate recognition domain; ficolins have a collagen-like domain and a fibrinogen-like domain.
Which proteins are associated with MBL in the lectin pathway?
MBL-associated serine proteases (MASPs) including MASP1, MASP2, and MASP3.
What role do MASPs play in the lectin pathway?
MASPs cleave C4 and C2 to activate the complement pathway, similar to the function of C1r and C1s in the classical pathway.
MASPs cleave C4 and C2 to activate the complement pathway, similar to the function of C1r and C1s in the classical pathway.
Formation of the membrane attack complex (MAC) that can lyse cells.
What are the components that form the membrane attack complex (MAC)?
C5b, C6, C7, C8, and multiple C9 molecules.
What is the function of the C9 protein in the MAC?
C9 polymerizes to form pores in plasma membranes, allowing the movement of water and ions, leading to cell lysis.
How does C5b-8 contribute to the formation of pores in the membrane?
C5b-8 complex inserts into the lipid bilayer and forms unstable pores, which are then stabilized by C9.
What structural similarity does C9 have with perforin?
C9 is structurally homologous to perforin and forms similar membrane pores.
What is the main function of the type 1 complement receptor (CR1, CD35)?
Promotes phagocytosis of C3b- and C4b-coated particles and clearance of immune complexes from the circulation.
Where is CR1 primarily expressed?
On bone marrow-derived cells such as erythrocytes, neutrophils, monocytes, macrophages, eosinophils, T and B lymphocytes, and follicular dendritic cells.
What type of complement fragments does CR2 (CD21) bind?
C3d, C3dg, and iC3b.
What is the role of CR2 on B cells and follicular dendritic cells (FDCs)?
On B cells, CR2 enhances activation and response to antigens; on FDCs, it traps antigen-antibody complexes in germinal centers.
What is the primary function of the type 3 complement receptor (MAC-1, CR3)?
Promotes phagocytosis of microbes opsonized with iC3b and binds to ICAM-1 to aid in leukocyte attachment to endothelial cells.
What distinguishes CR4 (p150,95) from MAC-1 (CR3)?
CR4 has a different _ chain (CD11c) but the same _ chain (CD18) as MAC-1 and likely has similar functions.
Where is the complement receptor CRIg found and what is its role?
CRIg is found on macrophages in the liver (Kupffer cells) and is involved in the clearance of opsonized bacteria and blood-borne pathogens.
What is the role of C5aR1 and C3aR?
Both are G protein-coupled receptors that mediate the proinflammatory effects of C5a and C3a, respectively.
What is the function of the C1q receptor?
Assists in the clearance of apoptotic bodies and protein fibers such as amyloid fibrils by binding C1q.
What is the main role of C1 inhibitor (C1 INH) in complement regulation?
Inhibits the proteolytic activity of C1r, C1s, and MASP2 to prevent excessive activation of the classical and lectin pathways.
What disease is caused by a deficiency of C1 INH, and what are its symptoms?
Hereditary angioedema; symptoms include intermittent edema in the skin and mucosa, abdominal pain, vomiting, diarrhea, and airway obstruction.
How do regulatory proteins like MCP, CR1, and DAF inhibit complement activation on normal cells?
By binding to C3b and C4b on cell surfaces, preventing the assembly of C3 and C5 convertases.
What is the role of Factor H in complement regulation?
Inhibits the binding of Bb to C3b, regulating the alternative pathway of complement activation.
