Module 1 Introduction of Immunology Flashcards
What are commensal organisms?
- They enhance human nutrients absorption; aid in digestion, and provide vitamins, B&K
- Protect against the disease and prevent colonization by other pathogens.
Problems with oral antibiotics?
Treatment also kills commensal bacteria & pathogens take over
What are pathogens?
Pathogens are infectious organisms that cause disease
What kind of pathogens are there?
Viruses; bacteria; fungi; parasites
Bacteria are classified as either gram-positive or gram-negative according to whether they stain purple or pink using the Gram stain procedure
Epithelium
General name for the layers of a cell that lines the outer surface and inner cavities of the body; protected by a tough impenetrable outer barrier
What are complements?
A system of soluble plasma proteins that commands the effector cells by tagging pathogens with molecule flag
Complement proteins can also kill, pathogens without assistance from effector cells by perturbing the integrity of the pathogen membrane
Two steps of the innate immune response?
- Recognize that a pathogen is present.
- Recruits effector mechanisms that kill or eliminate pathogens.
The overall innate immune responses is to induce a state of inflammation
Today the terms inflammation and innate immunity are used interchangeably
What are cytokines?
Small messenger proteins can induce inflammation & they are hormone like
Endothelium?
The thin layer of specialized epithelium, that lines the interior of a blood vessel
What is the clonal selection and clonal expansion?
The processes that select pathogen specific lymphocytes for proliferation and differentiation
Differences between innate immunity and adaptive immunity?
Innate immunity:
Rapid response within hours
Fixed
Limited number of specificities
Constant during the course of response
Adaptive immunity:
Slow response in days to weeks
Variable
Numerous highly selective specificities
Improved in the course of response, and I
What are memory cells?
Some of the lymphocytes that contributed it to a successful adaptive immune response persist in the body, and are selected it to provide a long-term immunological memory of the pathogen, these lymphocytes are memory cells
Memory cells enable subsequent encounters with the same pathogen to elicit is stronger and faster adaptive immune response; ones that terminate infection before there are any significant symptoms
What is acquired immunity?
The adaptive immunity based on immunological memory is called acquired immunity
What is a primary immune response and a secondary immune response?
The first time that a person makes an adaptive immune response to a pathogen is called a primary immune response
During the primary response, the person that acquired immunological memory
Secondary immune response: faster and stronger response, when encountering the same pathogen the second time due to immunological memory
The myeloid and lymphoid cell linage
See pic
Is hematopoietic stem cell self renewing?
Yes they are. SO “One for you and One for Me”
Hematopoietic stem cells divide to give daughter cells that are also hematopoietic stem cells in the process of self renewal
What are the characteristics of macrophages?
- Tissue resident.
- First to react in an infection
- Recruit neutrophils by secreting cytokines.
- Orchestrate local response to an infection.
What are neutrophils
Short-lived infantry of innate immunity; they form pus
Monocytes
They typically circulate in the blood;
Recruited by tissue resident macrophages to infection site and differentiate into macrophages
Dendritic cells
- Tissue resident.
- Determines when adaptive immunity is required.
- Carries intact and degraded pathogens to lymphoid tissues to initiate the adaptive immune response.
What are BCR and immunoglobulin?
Cell surface pathogen receptors of B cells
Plasma cells
Effector B cells / end stage of mature B cells
Antibody
A soluble form of the BCR secreted by plasma cells
TCR
T cell receptor, only expressed at cell surface receptors not soluble forms
Effector lymphocytes of innate and adaptive immunity
See pic
What is an epitope?
The part of the outer surface of an antigenic macromolecule that interacts directly with an antibody or B cell receptor is called the Epitope
Are there differences in antigens recognized by B cells and T cells?
The antigens are recognized by antibodies and BCRs are more versatile and can be a whole protein, carbohydrates and lipids. Ie BCRs can recognize a molecule’s three dimensional structure
The antigens recognized by TCRs are typically short peptides of 6 to 16 amino acids and they can only be recognized if presented by MHC molecules
MHC class I
Has closed groove on both ends and can only recognize max of 9 amino acids protein fragments
Can recognize the intracellular infections (all viral infections, and some bacterial infections)
Expressed by most cells
Binds CD8 T-cells
MHC class II
Has open grooves on both ends and can accommodate protein fragment with up to 20 amino acids
Recognize extra cellular infections
Expressed only by professional antigen presenting cells such as macrophages, dendritic cells, and B cells
Used to active CD4 Th cells
Primary lymphoid tissues
Where lymphocytes develop, and mature to the stage at which they are able to recognize and responded to a pathogen
The only primary lymphoid tissues in humans: bone marrow & thymus
B & T lymphocytes both originate from the bone marrow
B cells matures in the bone marrow
T cells matures in the thymus
Secondary lymphoid tissues
Any other lymphoid tissues are secondary lymphoid tissues.
Include:
lymph nodes;
Lymphatics;
Tonsil;
Spleen;
Peyer’s patch in small intestine
MALT
GALT etc..
Efferent lymph
The lymph leaving a lymph node
Humoral immunity
Immunity conferred by antibodies
Opsonization
Coating by antibodies or complement fragments
Opsonization alone cannot kill pathogens without the help of effector cells. Opsonization marks the pathogens for destruction and facilitates their recognition and ingestion by effector cells such as macrophages or neutrophils, which then phagocytose and kill the pathogen.
Opsonins such as antibodies or complement proteins bind to the surface of the pathogen, and the Fc receptor on the effector cell then binds to the opsonin, which facilitates phagocytosis. Once the pathogen is engulfed, the effector cell uses enzymes and other molecules to digest and destroy the pathogen.
Therefore, opsonization is an important step in the process of pathogen elimination, but it requires the help of effector cells to ultimately kill the pathogen.
What is lymph?
Originated in connective tissues, and collects plasma that leaks out of the blood vessels to become the extra cellular fluid and eventually returns to the blood
Lymph is not a pumped and the flow is sluggish
What is spleens function?
Spleen provides adaptive immunity to blood infections
The spleen is the organ that filters the blood to remove damaged erythrocytes
Its secondary function is that of a secondary lymphoid tissue, that defense in the body against a blood-borne pathogens
GALT
Gut associated lymphoid tissue
MALT
Mucosa associated lymphoid tissues
BALT
Bronchial-associate lymphoid tissues
