Immunology Worksheet Flashcards
Why is the B cell immune response called “antibody mediated?”
In the presence of a specific antigen and under the influence of a helper T cell (Th), B cells differentiate into plasma cells which secrete anti body specific to the antigen.
Give examples of “processed antigens”.
Viral coat protein, bacterial cell wall, proteins or toxins (exogenous antigens) are presented at the surface of an antigen presenting cell (APC) in association with MHC type II cell marker.
Where are “B cell receptors” located?
B-cell receptors are essentially a copy of the antibody that B cell is destined to produce. Expressed as an integral transmembrane protein.
What is “co-stimulation” and what is the effect of it?
A B cell is activated by the presence of an antigen (either processed or unprocessed) and then co-stimulated by interleukins from the matching Th cell.
Please list several actions of immunoglobulins/antibodies:
- Neutralize antigen
- immobilize bacteria
- agglutination
- activate complement
- enhance phagocytosis by opsonization
What is the source of plasma cells and what is their purpose?
in the presence of a specific antigen, and with the help of a specific Th, B cell differentiate into plasma cells which secrete specific antibodies.
What is the purpose of memory B cells?
The purpose of Memory B cells is to remain in the lymphatic tissue to serve as immunological memory. Next time the person sees that specific antigen, the B cells differentiate into plasma cells (and more Memory B cells) within a day or two, rather than 7-10 days with little or no infection the second time around.
Summarize the process of “B cell activation” (2 sentences).
B cell “sees” antigen or processed antigen, co-stimulated by specific Th cell, becomes antibody secreting plasma cell and memory B cells.
What are the targets of the T cell immune response?
1) bacteria or virally infected cells, recognize bacterial or viral proteins on the cell surface
2) cancer cells, recognize tumour cell markers
3) transplant issue, recognize another person’s MHC I (aka HLA, human leukocyte antigen)
What is the function of helper T cells?
Co-stimulate both cytotoxic T-cells (Th1) and B cells (Th2)
endogenous antigen - cytotoxic T cell (Tc)
exogenous antigen - (processed or not) B cells
What are the factors that are included in co-stimulation?
Th cell specific for the antigen
Interleukin 2 - Tc Cell
several interleukins - B cells
What are the actions of cytotoxic T cells?
- granzymes - enzymes that induce apoptosis in target cells, cells die, bacteria or virus inside the cell get eaten by phagocytes
- perforin and granulysin - perforate the cell membrane, the cell swells and bursts; granulysin bursts the microbe
What is the purpose of memory T cells?
Immunological memory, hang around and activate either memory B cells or memory T cells. Secondary response much faster.
Summarize the process of activation of cytotoxic T cells. (2 sentences)
Infected (or cancerous) body cell activates a specific Tc in the presence of the specific Th cell. Th cell produces interleukin 2 acts in a paracrine fashion with Tc cell. Proliferation and differentation of Tc cell into active Tc and memory Tc and memory Tc cells. Th cell also forms memory cells.
Characterize Primary Immune Response:
1st exposure, activates Th and B cells - memory Th and B cells and plasma cells which produce antibody; process takes 7-10 days (also Th and Tc active and memory cells)
