Genetic predisposition of autoimmune disease and B-cell chronic lymphocytic leukemia (B-CLL)

Autoimmune disease is a polygenic disease in which various genetic factors play crucial roles. The familial clustering and the association of HLA haplotypes have been well-recognized. There is a close association between chronic lymphocytic leukemia (CLL) and autoimmune disease. Like autoimmune diseases, CLL is the type of leukemia most often occurring among close relatives. The patients with CLL frequently share common HLA haplotypes with relatives with autoimmune disease. As the majority of CLL is of CD5+ B-cell type, and as CD5+ B cells are suggested to be involved in autoimmunity, certain regulatory abnormalities in the proliferation and differentiation of CD5 B cells may be involved in both B-CLL and autoimmune disease. I discuss here the possibility that different, but related, MHC haplotypes would predispose either to autoimmune disease or to B-CLL, based on our findings obtained from MHC (H-2)-congenic New Zealand mouse strains.