Humoral & Cellular Immunology

Our immune system distinguishes two categories of foreign substances. One category consists of antigens (foreign substances) that are freely circulating in the body. These include molecules, viruses, and foreign cells. The Second Category consists of self-cells that display aberrant MHC(Major Histocompatibility Complex) proteins. These aberrant MHC proteins can originate from antigens that have been engulfed and broken down (exogenous antigens) or from tumor cells and virus‐infected that are actively synthesizing foreign proteins (endogenous antigens).
Depending on the kind of foreign invasion, two different immune responses occur:
The Humoral response (or antibody‐mediated response) involves B cells that pathogens or recognize antigens that are circulating in the lymph or blood (“humor” is a medieval term for body fluid). In this, the antigens bind to B cells which lead to Interleukins or helper T cells stimulate B cells. In most cases, both an antigen and a stimulator are required to activate a B cell and initiate B cell proliferation. Further, B cells proliferate and produce plasma cells. The plasma cells bear antibodies with the identical antigen specificity as the antigen receptors of the activated B cells. The antibodies are released and circulate through the body, binding to antigens. Finally, B cells produce memory cells which provide future immunity.
The Cell‐mediated response involves mostly T-cells and responds to any cell that displays aberrant MHC markers, including cells invaded by pathogens, tumor cells, or transplanted cells. Self-cells or Antigen Presenting Cells (APCs) displaying foreign antigens bind to T cells. The Interleukins (secreted by APCs or helper T cells) stimulate activation of T cells. If endogenous antigens and MHC‐I are displayed on the plasma membrane, T cells proliferate, producing cytotoxic T cells. The Cytotoxic T cells destroy cells displaying the antigens. If exogenous antigens and MHC‐II are displayed on the plasma membrane, T cells proliferate, producing helper T cells. The Helper T cells release interleukins (and other cytokines), which stimulate B cells to produce antibodies that bind to the antigens and stimulate nonspecific agents (NK and macrophages) to destroy the antigens.
 
  • T cells and B cells
  • Adaptive immunity
  • Antigen receptor sites
  • Immunoglobulins
  • Functions of Antibodies
  • Inflammation and Inflammatory factors
  • Complement system
  • Monocytes and Macrophages
  • Non-antibody immunity
  • Resistance to Intracellular Microbial and Viral infection

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Humoral & Cellular Immunology Conference Speakers