M. Guerisoli, M. Giacomini, C. Ruggiero
DIST, University of Genova

The Hla complex, that is the human system of histocompatibility, is composed by intrinsic proteins that are present on all the cells and that behave like antigens. When these proteins come to contact with the immune system of one different individual, they are recognized like strangers and provoke the immune answer. Its genes are situated on the short arm of chromosome 6, and they have been subdivided in two main classes: I, that comprises genes of type A, B and C and II, that comprises genes of type DP, DQ, DR. The antigen of class I are present on all the nucleate cells of the organism. This distribution of the antigens of class I stress their importance as acknowledgment markers between that the organism recognizes like pertaining to it (self) and that that is stranger (non-self). It can be assumed therefore that the HLA is at the basis of the procedure of immunity acknowledgment. They are fundamental for the study of the problem of the refusal in the transplants.