2015年B免疫应答8年制TIANOCT20概述.ppt

Immunity and the Immune Response System Humoral or B-Cell Mediated Immune Response Produces secreted antibodies (proteins) Bind to antigens and identify the antigen complex for destruction. Each B lymphocyte makes a unique antibody molecule (immunoglobulin or Ig). Over a million different B lymphocytes are produced in each individual. Activation of B Lymphocytes and Production of Antibodies Immunologically Naive B Cell Receptor Complex 第一节 B细胞对TD抗原的免疫应答 Two-Signal Model of Humoral Immune Response Several important modifications occur in the GC; somatic hypermutation, affinity maturation and isotype switching. IgA+ plasma cells in green, IgG+ plasma cells in red. X-linked Hyper IgM syndrome: IgG, IgA, IgE deficiency 初始T细胞多由树突状细胞活化，记忆T细胞可识别多种APC提成的抗原。 再次应答过程中，记忆性B细胞作为APC摄取、处理抗原，并将抗原提呈给记忆性Th细胞。 B细胞对TI抗原的免疫应答，使机体在TD抗原免疫应答建立之前（如感染初期）即可产生特异性抗体。 针对某些胞外细菌TI-2抗原（如荚膜多糖）的特异性抗体，可促进巨噬细胞对病原体的吞噬。 第三节 体液免疫应答的一般规律 The Primary Immune Response Four phases of the primary response a lag phase when no antibody is detected a log phase in which the antibody titer rises logarithmically a plateau phase during which the antibody titer stabilizes a phase (decline) during which the antibody is cleared or catabolized Features of primary and secondary antibody responses. Primary and secondary antibody responses differ in several respects. In a primary response, naive B cells in peripheral lymphoid tissues are activated to proliferate and differentiate into antibody-secreting cells and memory cells. Some antibody-secreting plasma cells may migrate to and survive in the bone marrow for long periods. Features of primary and secondary antibody responses. In a secondary response, memory B cells are activated to produce larger amounts of antibodies, often with more heavy chain class switching and affinity maturation. Many of the features of secondary responses (e.g., heavy chain isotype switching, affinity maturation) are seen mainly in responses to protein antigens,