Immunology

See Also

• Cell mediated immunity
• Natural Killer (NK) Cells
• Cytokines

Description

The relationship between lymphocytes and antigen-presenting cells is complicated and depends on a huge molecule called the Major Histocompatibility Complex (MHC) a sort of socket by which lymphocytes recognize and process foreign antigens. The biological role of MHC proteins is to bind small foreign antigens and to "present" these at the cell surface for the inspection by the T cell lymphocytes. Like blood type, the MHC is a molecular and genetic delineator of 'self': For example, It has a major influence on graft and organ transplant survival. Individuals identical for this region can exchange grafts more successfully than MHC non-identical combinations. It has been hypothesized that the MHC interacts with our blood type antigens in such day-to-day activities as cell-cell recognition, association and aggregation. The relationship appears to be quite important to the development of our immune system during the 'education' of lymphocytes in the thymus gland. T-cells comprise 80% to 90% of circulating lymphocytes, and may survive up to 30 years. T-cells can be categorized as helper/inducer (CD4) cells and as suppressor/cytotoxic (CD8) cells.

Helper T-cells

Like the name implies, T-helper cells respond to soluble antigen and 'help' induce B-lymphocytes to secrete antibodies.

T helper cells exist in two sub classes::

• [TH1 cells]? produce cytokines that promote cellular immune responses. These cytokines include interleukin-2 (IL-2), interferon-gamma (IFNg), and [Tumor necrosis factor]?-beta (TNFb),.
• [TH2 cells]? produce interleukins 2, 4 6 and 10, all of which prompt B cells to produce antibodies.

Supressor T-cells

Cytotoxic or cytolytic T cells lyse (kill) cells that produce foreign antigens, such as tumor cells, virus-infected cells, and foreign tissue grafts Cytoxic T cells are identified by the presence of the CD8 marker. These cells can suppress the immune response, and are sometimes referred to as 'Supressor-T cells.'

Discussion

Blood group antigens are expressed on the cell surface at definite stages of cell differentiation during embryonic growth, the growth of organs, tissue repair, regeneration, remodeling and maturation

Blood group antigens appear to help cells during the process of 'sorting-out' as they begin to assume more mature functions. In this event the blood type antigens play a role of key structural determinants in cell-cell recognition, association and aggregation and self-non-self discrimination, during thymic education. This process appears to be very closely linked to the functioning of the MHC system; the interaction of blood type antigens and the MHC may be the main mechanism by which mutated cells are routinely cleared by the immune system.

References

• Glinsky GV The blood group antigen-related glycoepitopes: key structural determinants in immunogenesis and AIDS pathogenesis. Med Hypotheses 1992 Nov;39(3):212-24

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