| Abstract: | The major histocompatibility complex (Mhc) is a set of genes that codes for plasma-membrane associated proteins, which are primarily expressed on the cells and tissues of the immune system. The proteins serve as cell markers during the initiation phase of immune response. T lymphocytes recognize Mhc molecules with their receptors when they recognize a foreign antigen on the surface of an antigen presenting cell. The functional Mhc genes are highly polymorphic. One consequence of this polymorphism is the existence of nonresponders to foreign antigens. Certain combinations of self Mhc molecules and nonself antigens fail to stimulate an immune response. A possible explanation for this nonresponsiveness is the need to make an individual unresponsive to (tolerant of) its own proteins. Tolerance leads to the inactivation of certain T cell clones; thus, if the same clones also happen to recognize a particular foreign antigen, the individual becomes unresponsive to this antigen as well. It then contains a blind spot in its repertoire. |
