《微生物学》课程PPT课件讲稿（英文版）Lecture 7 Interactions of Phagocytes and Other Immunological Cells

Production of ab and activation of Macrophages and Cytotoxic T Celis T-Dependent T-Independent BIOL 533 Lecture 7

BIOL 533 2 Lecture 7 Production of Ab and Activation of Macrophages and Cytotoxic T Cells • T-Dependent • T-Independent

T-Dependent Activation带 EXtracellular pathogens Digested by macrophage--Ag complexed MHC class ii (present only in macrophage and few other cell types) Stimulates helper T cells(tH2) to find B cells, recognize particular peptide fragment ab Helper T cells(CD4+ cells; THi) produces FNv and activates macrophage BIOL 533 Lecture 7

BIOL 533 3 Lecture 7 T-Dependent Activation • Extracellular pathogens – Digested by macrophage—Ag complexed MHC class II (present only in macrophage and few other cell types) – Stimulates helper T cells (TH2 ) to find B cells, recognize particular peptide fragment Ab – Helper T cells (CD4+ cells; TH1 ) produces IFN and activates macrophage

T-Dependent Activation带 Intracellular pathogens Digested when released from dying host cell Peptide Ag presented on MHC class I Proliferation of cytotoxic T cells(CD8+) BIOL 533 Lecture 7

BIOL 533 4 Lecture 7 T-Dependent Activation • Intracellular pathogens – Digested when released from dying host cell – Peptide Ag presented on MHC class I – Proliferation of cytotoxic T cells (CD8+)

a Processing CHO and Lipid Ag y LPS interacts directly with B cells (independent of T cells CHO Ag largely independent of T cells, but some involvement(production of cytokines; necessary for maximal B cell activity) BIOL 533 Lecture 7

BIOL 533 5 Lecture 7 Processing CHO and Lipid Ag • LPS interacts directly with B cells (independent of T cells) • CHO Ag largely independent of T cells, but some involvement (production of cytokines; necessary for maximal B cell activity)

T-Dependent mechanism Macrophage presents part of Ag and own class II MHC to T-helper cell(signal #1) Also makes ILl 6 signal #2) IL1 6 stimulates t cell clone to divide and make il2 4-6 ILl also stimulates hypothalamus to raise body temperature, enhancing T cell action BIOL 533 Lecture 7

BIOL 533 6 Lecture 7 T-Dependent Mechanism • Macrophage presents part of Ag and own class II MHC to T-helper cell (signal #1) • Also makes IL1 6 (signal #2) – IL1 6 stimulates T cell clone to divide and make IL2 4-6 – IL1 also stimulates hypothalamus to raise body temperature, enhancing T cell action

T-Dependent mechanism IL2 4-6 stimulate T-helper cells to multiply These t cells associate with b cells that have correct Ag MHC II complex and secrete B cell growth factors(BCGf that cause B cells to multiply BIOL 533 7 Lecture 7

BIOL 533 7 Lecture 7 T-Dependent Mechanism • IL2 4-6 stimulate T-helper cells to multiply – These T cells associate with B cells that have correct Ag— MHC II complex and secrete B cell growth factors (BCGF) that cause B cells to multiply

T-Dependent mechanism The number of b cells increase T-helper cells produce other cytokines(BCDF These cause some B cells to stop dividing, differentiating into plasma cells and produce ab Also B cell recognizes its Ag through its surface IgM receptor(signal #1 for b cell), subsequently triggered to proliferate plasma cells ab BIOL 533 Lecture 7

BIOL 533 8 Lecture 7 T-Dependent Mechanism • The number of B cells increase, T-helper cells produce other cytokines (BCDF) – These cause some B cells to stop dividing, differentiating into plasma cells and produce Ab – Also B cell recognizes its Ag through its surface IgM receptor (signal #1 for B cell), subsequently triggered to proliferate plasma cells Ab

T Cell Biology MHC molecules Major Histocompatibility Complex Found on plasma membrane Class i found on most nucleated body cells Class ii found only on leukocytes involved in immune response(macrophage, Ag presenting cells, B cells) Class i and Il Ag processed differently BIOL 533 Lecture 7

BIOL 533 9 Lecture 7 T Cell Biology • MHC molecules – Major Histocompatibility Complex – Found on plasma membrane – Class I found on most nucleated body cells – Class II found only on leukocytes involved in immune response (macrophage, Ag￾presenting cells, B cells) – Class I and II Ag processed differently

T Cell Biology Class i molecules bind to peptides found in cytosol (e. g replicating viruses) Endogenous proteins are digested by natural processes Peptides from cytosol endoplasmic reticulum BIOL 533 Lecture 7

BIOL 533 10 Lecture 7 T Cell Biology • Class I molecules bind to peptides found in cytosol (e.g., replicating viruses) • Endogenous proteins are digested by natural processes • Peptides from cytosol endoplasmic reticulum

T Cell Biology Within ER, class I MHC heavy chain synthesized and associates with B2 microglobulin Dimer binds peptide plasma membrane If peptide is foreign passing CD8+ T cell (cytotoxic) recognizes, releases cytokines destroys cell BIOL 533 Lecture 7

BIOL 533 11 Lecture 7 T Cell Biology • Within ER, class I MHC heavy chain synthesized and associates with 2 microglobulin • Dimer binds peptide plasma membrane • If peptide is foreign, passing CD8+ T cell (cytotoxic) recognizes, releases cytokines, destroys cell