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Announcements. Have possible topics for paper chosen by Friday! . The Cells Important in Immunology. A Closer Look. B lymphocytes (B cells) T lymphocytes (T cells). Lymphocytes:. B cells: Surface receptor = Immunoglobulin (Ig). Humoral Immunity. kuby. Helper T cells (Th cells):
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Announcements • Have possible topics for paper chosen by Friday!
The Cells Important in Immunology A Closer Look
B lymphocytes (B cells) T lymphocytes (T cells) Lymphocytes:
B cells: Surface receptor = Immunoglobulin (Ig). Humoral Immunity. kuby
Helper T cells (Th cells): T cell Receptor (TCR) CD4+ Produce cytokines & direct immune responses. Cytotoxic T cells (Tc or CTL): TCR+ CD8+ Cytotoxic T cells:
Large granular lymphocyte: NK cells or null cells lack TCR, CD4, & CD8 Cytotoxic- cancer cells & intracellular pathogens. Innate immune responses.
Dendritic Cells: Travel to most tissues & establish residency. Skin- langerhans cells Organs & Lymphoid tissue: Interstitial DC & Interdigitating DC Antigen Presenting cells (APC) presents antigen to T cells.
Follicular dendritic cells- Lymph nodes Not derived from the BM Role in the humoral immune response.
Monocytes enter circulation & after ~8 hrs enter tissues. Macrophages: 5-10 X larger Intracellular organelles increase in size & numbers. Increased phagocytic capacity. APC Secrete cytokines. Mononuclear cells Treadmilling Macrophage
Granulocytes Neutrophils Eosinophils Basophils
Smaller than mf. Short lived: ~ 3 days Not a permanent resident of healthy tissues. Leukocytosis. Neutrophil
Basophil: Heavily granulated Nonphagocytic Role in allergies Eosinophil: Bilobed nucleus Less phagocytic than neutrophils Important in fighting parasites
Mast Cells: Reside in connective tissues & near small blood vessels. Important in innate responses. Inflammation Carrier mediators in granules (histamine).
The organs of the Immune System: The Lymphoid Tissue
Fig. 5.1, Parham • Primary Lymphoid Tissue: • Location where lymphocytes develop & mature to a stage where they can interact with Ag. • Bone Marrow- B cells • Thymus- T cells
Secondary Lymphoid Tissue: • Tissue traps antigen & provides sites for lymphocytes to interact & respond to antigen. • Lymph Nodes • Spleen • Mucosal associated lymphoid tissue (MALT) • Cutaneous associated lymphoid tissue (CALT)
Cortex: outer layer B cells & mf Paracortex: T cells, dendritic cells, & mf Medulla Plasma cells Germinal centers: Few T cells at the center & are surrounded by B cells. p. 17
Lymphatic System: anastomosis- to run into each other, network of branches.
Capillaries Interstitial fluid Fig. 2-16, p. 46, kuby Immunology, 5th edition
Every minute, 1X106 lymphocytes leave the blood & enter the lymphatics.