Der Haupthistokompatibilitätskomplex und die Unterscheidung zwischen Selbst und Fremd durch das Immunsystem

The major histocompatibility complex (Mhc) is a cluster of closely linked genes which are involved in the distinction between self and non-self. The genes fall into two classes, I and II, which are evolutionarily related but specialized to performing somewhat different functions. The Mhc genes code for proteins which are seen together with foreign substances by the thymus-derived lymphocytes. These lymphocytes thus recognize simultaneously self (Mhc molecules) and non-self (foreign antigen). Some of the Mhc genes are highly polymorphic and this polymorphism probably represents a compensation for the fact that certain combinations of Mhc molecules and antigen fail to be recognized by the T lymphocyte.