Immunology Flashcards
What are the 3 defining characteristics of the innate immune system?
- response is antigen independent
- immediate maximal response
- no memory is formed
What are the 3 defining characteristics of the adaptive immune system?
- response is antigen dependent (or antigen specific)
- lag time between exposure and maximal response
- immunologic memory is formed
The three tenants of adaptive immunity are:
- Specificity
- Self recognition
- Memory
Which immune cells differentiate from the lymphoid stem cell?
Lymphocytes:
- T cell
- Natural Killer cell
- B cell:
- plasma cell
- memory B cell
Which 6 immune cells differentiate from the myeloid progenitor cell?
Granulocytes
- neutrophil
- eosinophil
- basophil
- mast cell
- monocyte
- dendrittic cell
- machrophage
What are the two major categories of immune cells?
Lymphocytes and granulocytes
What activates neutrophils?
Tumor necrosis factor (a cytokine)
Which immune cell makes up 60-65% of WBCs?
Neutrophils
Which cells are polymorphonuclear and phagocytic?
Neutrophils
How common are basophils? What do they release, and what part of the immune system triggers that release?
These cells make up 0.1-0.3% of WBCs. They release histamines and are triggered by IgE antibodies.
What cells are triggered to release histamine by IgE?
Basinophils and Mast cells (mast cells are found in the tissue only)
Which immune cells are involved in the destruction of parasites?
Eosinophils
What two cells differentiate from monocytes when they migrate into the tissue and become activated?
Macrophages and dendritic cells
Which cells have a multilobed nucleus?
Macrophages (bi-lobed) neutrophils (more lobes the older they get)
In what kind of tissue will you find macrophages?
Reticuloendothelial (liver, spleen, bone marrow, CNS, GI)
What are the two primary functions of macrophages?
Phagocytosis and antigen presentation
What are characteristics of dendritic cells?
- mobile, branched
- highly phagocytic
- part of adaptive immune response
- antigen presenting cells
Where do T lymphocytes mature?
Thymus
What are the two main subtypes of T cells and what do they do?
T-helper cells: coordinate immune response
and
T cytotoxic cells: destroy infected cells
Where do B lymphocytes mature?
Bone marrow and fetal liver
What are the subtypes of B lymphocytes and what do they do?
Plasma cells: create antibodies
And
Memory B cells: retain blueprints for antibodies to specific antigens to allow for faster immune response
How do natural killer cells kill their prey?
Creating holes in the cell membrane
What kind of cells do natural killer cells attack?
Infected human (self) cells , but not the microbe that has infected the cell
Which immune system contains natural killer cells?
Innate - they do not require presentation of an antigen to attack
Which parts of the immune system use cytokines to stimulate cells?
Both innate and adaptive
Cytokines are chemical messengers that induce ? In immune cells
Chemotaxis (follow a chemical gradient to a destination)
Diapedesis (movement into tissue from circulation)
What are common types of cytokines? What is the major function of each type?
- Interleukins: WBC communication
- tumor necrosis factor: tumor suppression
- interferons: disrupt viral replication (interfere!) AND activate immune cells
What are the peripheral lymphoid organs?
- Lymph nodes
- spleen
- tonsils
- adenoids
- appendix
What are the primary lymphoid organs?
- Bone marrow
- thymus
What kind of cells are in germinal centers of lymph nodes?
Dividing lymphocytes - both T and B cells.
Lymphocytes are mitotic, which is why lymph nodes swell when you are sick
What about T cells contributes to reduced immunocompetence as we age?
T cells mature in the thymus, which involutes during puberty. After puberty no new lines of T cells are created, so when a T cell line reaches it mitotic limit, we have fewer of them!
What is the main function of the spleen?
To filter and destroy old RBCs
To host lymph tissue
The tonsils and peyers patches (in the GI tract) are what kind of ALT?
MALT: mucosal associated lymphoid tissue
What is the function of MALT?
- phagocytosis
- secretion of immunoglobulin (IgA)
What makes an immune cell immunocompetent?
Maturation within primary lymph organ —> it means they are capable of mounting an immune response
The thymus is responsible for what two things, in addition to producing what immune processing hormone?
- immunogenesis (children)
- T cell maturation
- production of thymosin, which functions in processing T cells and developing B —> plasma cells
What is DiGeorge syndrome, and what are some characteristics?
A condition of thymic deficiency resulting from a deletion on chromosome 22
Depending on the length of the deleted segment:
- t cell deficiency
- congenital heart disease, and other cardiac anomalies
What are immature T cells in the thymus?
Thymocytes
Thymocytes develop into two types of cells, what are their markers, and subpopulations?
CD4 = HELPER T cells
- TH-1: cell mediated immune response
- TH-2: activate B cells (stimulate antibody production)
CD8 = CYTOTOXIC cells
Destroy virus infected cells and tumor cells
What is negative selection?
When a failing T cell enters apoptosis
What is the first layer of the innate immune system, and what are some of it’s feature functions?
Skin
- mechanical barrier
- shedding
Skin resistance increases with age, improving it’s efficacy as a barrier to disease due to what compositional change?
Increased fatty acids
What is the second layer of the innate immune system, and what are some of it’s features?
Mucosal membranes:
- cilia remove microbes
- GI tract has enzymes and acids
What antimicrobial substances does the body produce to prevent infection?
- sweat
- lysozyme (skin, tears, mucous)
- saliva
- stomach acid
How do the body’s normal flora help protect against infection?
Competitive exclusion of pathogens
What is the difference between microbiota and microbiome?
Microbiota = population of microbes living on and in humans
Microbiome = the genomes of the microbial population living on humans
What is the primary sensory for the immune system by which it becomes aware of the presence of a pathogen?
The toll-like receptor, which recognizes compounds unique to microbes (like bacteria DNA, which is different than ours)
What is an immune complement?
A series of proteins always present in the blood that participate in microbe destruction when activated - often they trigger protein cascades
What are the three functional strategies of complement proteins?
O - Opsonization
I - Inflammation
L - Lysis
What is opsonization?
The process of coating a pathogen with proteins that correspond to binding sites on phagocytic cells, making it easier for the pathogen to be consumed.
What role does inflammation play in immune response?
- dilation of blood vessels - induction of fever
What is lysis (related to immune response)?
Lysis is the loss of cellular contents following a membrane attack complex (MAC) that makes holes in the membrane of the pathogen
What is the purpose of blood vessel dilation in immune response?
Dilation increases vessel permeability, allowing for more migration of cells into damaged or infected tissue. (Swelling, redness, pain may result)
Inflammation also promotes the chemotactic attraction of macrophages, neutrophils, and natural killer cells to an area of infection.
What is the purpose of fever in immune response?
Fever (induced by interleukin-1, or IL-1) is an attempt to weaken pathogens by shifting body temperature away from ideal replication temp (at least bacteria replicate at physiologic normal for humans)
What is the most antigenic substance or class of molecule?
Proteins
Lipids and polysaccharides can also be antigenic
What is a hapten? What is an example?
A hapten is an antigen that is too small to be recognized on its own, but that will be recognized as a pathogen when bound to a larger molecule.
Poison oak is an example