MBIO Exam #2-Receptors

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Only B lymphocytes
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Terms in this set (23)
Only B lymphocytes
B cell receptors (BCR) recognizes Ag.
On T lymphocytes
T cell receptors (TCR) recognizes Ag.
Two Types of Adaptive Immune Response
Humoral (Ag)
Cell-Mediated
TH
Helper T cells.
Humoral Response-Antibody Mediated
1A. Antigen Presenting Cell (APC) selects correct TH type from repertoire of TH cells.
1B. APC presents antigenic determinant (via MHC) to TCR on TH cells.
2A.IL-1 from APC causes differentiation of TH cells to TH2 cells.
2B. TH2 cells can recognize antigen on B cells.
3A. Meanwhile: from a repertoire, B cell attached to and phagocytizes a complementary Ag via BCR. The B cell then displays the Ag via MHC.
3B. TH2 selects B cell with BCR to the matching antigen from a repertoire of B cells via Ag on MHC.
4. TH2 cells secretes IL-4. Activates B cell causes B cell clone to proliferate.
5A. Primary vs. Secondary Response.
MHC: Major Histocompatility Complex
Basis for tissue rejection.
Class I: all nucleated cell (not RBCs)
Class II: B cell or APC.
Clonal Selection.
TH2 selects B cell with BCR to the matching antigen from a repertoire of B cells via Ag on MHC.
Proliferating plasma cells
Actively produce antibody. This is the primary response.
Memory B cells
Tiny proportion of activated B cells survive for months or years. Do not secrete antibody. Thus, these cells are activated upon second exposure to Ag. This is the secondary response.
Primary Response
B cells activated and memory cells produced and the initial response is slow.
Secondary ReponseMemory cells immediately differentiate into plasma cells, faster and greater response, and second exposure to Ag: faster and greater response.Humoral Response-Antibody Mediated Summary1. Antigen presentation 2. Differentiation of T cells 3. Clonal Selection 4. Activation of B cells 5. Primary vs. Secondary ResponseCell-Mediated ResponseFor fighting intracellular pathogens and abnormal cells. 1. Intracellular pathogens and abnormal cells via MHC II on surface of Dendritic cell (DC). 2. DC's (secrete IL-12) causes TH cells to differentiate to TH1 cells. 3. Via antigen on MHC1. DC cells recognize cytotoxic T cells (TC)) in the TC cell receptor. 4. Thus, specific TC cells are activated. TH1 cells secrete IL-2 and Gamma Interferon. 5. Primary vs. Secondary Response- Memory T cells work like Memory B cells.TH1 cells secrete IL-2 and Gamma Interferon.Stimulate TC cells having TCR complementary to AG, Il-2is trigger: TC cells divide, forming memory TC cells and more TC cells, and active TC cells secrete IL-2 and become self-stimulatory.Clonal ExpansionTC cells divide, forming memory TC cells and more TC cells.Primary: Cell-Mediated1. Antigen presentation. 2. Differentiation of T-cells 3. Clonal Selection 4. Activation of Cytotoxic T cells (TC) 5. Primary vs. Secondary ResponseHow do TC cells kill?"Non-self" antigens are displayed on the surface of: virus infected cells, caner cells, and tissue transplants.Mechanism of Killing Process: Perforin-Granzyme PathwayTC cells contain the cytotoxins: Perforins and Granzyme. Cytotoxins released when TC cells first attaches to target cells (displaying antigen). Apoptosis inductin in target cells: Perforin creates pores through which granzyme (serene protease) enters to induce aptosis. Move on to other target cells.Clonal DeletionT-Cells: The thymus expresses all epitopes of normal proteins. T-cells recognizing normal epitopes dies (apoptosis). B-Cells: Stem cells in bone marrow generate B-cells with all possible BCR's. B-cells with BCR for self bind to self antigens and die (apoptosis). Thus, self-reacting clones are deleted. Immune ToleranceImmune ToleranceSystem does not attack self.Humoral ResponseB cells make antibodies, which interact with antigens on pathogens. Pathogens inactivated.Cell-Mediated ResponseT cells induce cytotoxic TC cells, which target and kill cells displaying pathogen antigens.Both systemshave memory cells for fast response upon subsequent exposures to the antigen. Both systems show immune tolerance.