IMSE311 LEC-Week 3 PDF

IMSE LEC: Week 03 - How B Cell Matures INNATE IMMUNE SYSTEM → Since birth → providing a quick, non-specific response to all invaders pathogens through barriers and immune cells. EXTERNAL INNATE IMMUNE SYSTEM → First line of defense They block the pathogens from entering the body. Skin...

IMSE LEC: Week 03 - How B Cell Matures INNATE IMMUNE SYSTEM → Since birth → providing a quick, non-specific response to all invaders pathogens through barriers and immune cells. EXTERNAL INNATE IMMUNE SYSTEM → First line of defense They block the pathogens from entering the body. Skin Mucous membranes Normal Flora Secretions Etc INTERNAL INNATE IMMUNE SYSTEM → Phagocytic cells engulf and digest pathogens. They respond to invaders that breach external defense. APCs: They carry the information about the antigen and they present it to the adaptive immune system to make an antibody. ADAPTIVE IMMUNE SYSTEM → More precise because they target specific pathogens and build memory for future protection that leads to faster and stronger response. T cells: After receiving the information from APCs, the T cell will respond by releasing cytokines to B cells. Cytokines: (messenger cell) → contains the information needed about the antigens. B cells: Make antibodies after meeting with the cytokines, and wait until the same pathogens reappear, then the immune system can respond quickly and effectively. Antibodies: can also help in the Internal Innate Immune System by enhancing innate immunity function and fight the pathogens. Natural Killer (NK) cells: Also part of the innate immune system and help defend the body by directly attacking and killing virus-infected or cancerous cells. Pathogen-associated Molecular Patterns (PAMPs) → They can recognize Peptidoglycan in G+ bacteria Lipoproteins in G- bacteria Zymosan in yeast Flagellin in bacteria with flagella Toll-like receptors → detects organism that will attach to them FIGURE 2-2 Toll-like receptors on a WBC membrane. Each of the 10 different TLRs recognizes a different pathogenic product. TLRs found on the cell surface tend to form dimers to increase chances of binding to a foreign substance. Pathogen Recognition Receptor (PPR) Found in: WBC Macrophage Dendritic cells Neutrophil Eosinophil Mast cells Monocyte Epithelial cell T cells IMSE311-Lec: Mr. Hanzel Tolentino Razon, Christ Audrey Jhoy R. BSMLS 3-Y1-6 1. Activates phagocytes (Phagocytosis) 2. Cells secrete proinflammatory cytokines and chemokines 3. Cytokines and chemokines released trigger the adaptive immune response Naive → Not activated Antigen Antibody Complex → When antigen get paralyzed ORGANS OF THE IMMUNE SYSTEM Primary and Secondary Lymphoid Organ Function Maturation of B and T cells Activation of T and B cells; Where contact with antigen happens Production Antigen-Independent Antigen-Dependent Members Bone Marrow and Thymus Spleen, lymph nodes, MALT PRIMARY LYMPHOID ORGANS BONE MARROW → Largest tissue in the body and fills all long flat bones. Two Types of Bone Marrow Yellow → Fats Red → Blood cells ** The yellow is increasing when getting older IMSE311-Lec: Mr. Hanzel Tolentino Razon, Christ Audrey Jhoy R. BSMLS 3-Y1-6 THYMUS → Small, flat, bilobed organ found in the thorax. Gradually shrinks in size as human ages; Also an endocrine organ SECONDARY LYMPHOID ORGANS: SPLEEN Largest secondary lymphoid organ; found on the ULQ of the abdomen just below the diaphragm Characterized as a large discriminating filter, as it removes old and damaged cells and foreign antigens from the blood ○ 2 Main Types of Splenic Tissue: Red Pulp: involved in Culling process White Pulp : Contains lymphoid tissue that is arranged around arterioles as PALS (Periarteriolar Lymphoid Sheath) T cells are found near the central arteriole Naive B cells are found on primary follicles Activated B cells are found on Secondary Follicles in the germinal centers Marginal zone contain macrophages SECONDARY LYMPHOID ORGANS: LYMPH NODES Junctional filter of the lymphoid system Lymph nodes provide ideal environment for contact with antigen from tissues Serve as central collecting points for lymph fluid from adjacent tissues Sizes may range from 1mm to 25 mm Parts: Outer Cortex – macrophage, resting B cells, follicular dendritic cells Secondary follicles – antigen-stimulated proliferating b cell Germinal center – plasma cells and memory b cells Paracortex – T cells Inner Medulla – T cells, B cells, macrophage and numerous plasma cells SECONDARY LYMPHOID ORGANS: MALT Mucosal-associated tissue known as MALT Found in gastrointestinal, respiratory and urogenital tracts wherein main ports of entry of pathogens ○ Examples: Tonsil Appendix Peyer’s patches IMSE311-Lec: Mr. Hanzel Tolentino Razon, Christ Audrey Jhoy R. BSMLS 3-Y1-6 B CELL MATURATION Pro-B Cell (Progenitor B cell) Growth factor of Pro-B cell from stem cell E2A, EBF (early B-cell factor), interferon regulatory factor (IFR8), and paired box protein 5 (PAX5), IL7 Markers: CD 19, CD45R, CD43, TdT, RAG-1 and RAG-2 enzyme Main function: the rearrangement of genes that code for the heavy and light chains of an antibody molecule Pre-B cell (Precursor B cell) Markers: receptor that is made up of 2 heavy chains and a surrogate light chain Main function: synthesis of heavy chains. First is μ. Immature Cell Markers: complete IgM antibody, CD21, CD40, Class II MHC, Main function: preparation for antigen-specific response IMSE311-Lec: Mr. Hanzel Tolentino Razon, Christ Audrey Jhoy R. BSMLS 3-Y1-6 Mature cell Markers: complete IgM and IgD antibody, MHC class II Can be marginal zone mature b cell or follicular mature B cells Main function: wait in the secondary lymphoid organs to be activated Plasma cell Spherical and ellipsoidal, 10-20um Has abundant cytoplasmic immunoglobulins but little to no surface Ig The most fully differentiated lymphocyte Not found in the blood; only germinal center of the lymphoid organs or the bone marrow Main function: antibody production Classes of antibodies Antibody structure Tetrapeptide made up of a four-chain unit molecule: Heavy chain → With five principal antigenic types with their corresponding Ig. (gamma, alpha, mu, delta, epsilon) Light chain → With two antigenically defined types: kappa and lambda IMSE311-Lec: Mr. Hanzel Tolentino Razon, Christ Audrey Jhoy R. BSMLS 3-Y1-6