Immune System

There are approximately 106-108 antibody specificities referring to different antigenic structures (epitopes), and a specific antigenic molecule will interact with and activate only a small proportion (<0.1%) of the antibody-producing cells. B cells are precursors of antibody-producing plasma cells, and T cells are thymus-derived cells that produce a number of stimulatory agents for B cells. The ability of a B-cell-derived immune (memory) cell to produce antibodies depends on a number of stimulatory factors as well as transpositions of variable genetic elements of the immunoglobulin structure, a subject of intense concentration in molecular genetics. Stimulatory activities are derived from thymus-derived cells (T cells) usually considered to be helper T cells (Figure 17-1).

The thymus contains T-cell lymphocytes, which in turn produce factors that regulate the expression of immunoglobulins by B-cell lymphocytes. T cells enter circulation from the thymus, as do B cells from bone marrow. Phagocytic cells (macrophage, antigen-processing cell, APC) are also involved in the immune process.

When an antigen (a foreign substance) enters the organism, B cells produce immunoglobulins with helper T-cell action. Antibodies on the surface of T cells with the same specificity as those produced by the activated B cells bind the antigen, and the complex is then transferred to a macrophage cell that ingests and destroys the antigen. This scheme (Figure 17-1) also depicts the factors contributed by helper T cells that stimulate antibody production. This chapter concentrates on a family of peptide hormones that regulate the proliferation and maturation of precursor lymphocytes into immunologically competent cells.

When an antigen is recognized by a T cell, a signal transduction mechanism involving the T-cell receptor comes into play. This series of events is shown in Figure 17-2. This figure shows the signal transduction events


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Cure Tennis Elbow Without Surgery

Cure Tennis Elbow Without Surgery

Everything you wanted to know about. How To Cure Tennis Elbow. Are you an athlete who suffers from tennis elbow? Contrary to popular opinion, most people who suffer from tennis elbow do not even play tennis. They get this condition, which is a torn tendon in the elbow, from the strain of using the same motions with the arm, repeatedly. If you have tennis elbow, you understand how the pain can disrupt your day.

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