Blood antiphospholipid antibody levels are influenced by age, sex and HLA-B8,DR3 phenotype.

Antiphospholipid antibodies (APA) are known to be associated with a number of seemingly heterogeneous pathological conditions that are part of the antiphospholipid syndrome, formerly called anticardiolipin syndrome. Recent studies on the mechanism of action of these autoantibodies suggest that we are dealing with a new autoimmune syndrome which may occur either in a primary form or in the context of other autoimmune diseases, mainly systemic lupus erythematosus (SLE). Moreover, increased levels of APA have been found in elderly subjects, who are known to display increased frequency of autoimmune phenomena. It is well known that many autoimmune diseases, including SLE, are associated with HLA antigens, particularly with HLA-B8,DR3 phenotype. In our study, APA serum levels were analyzed in 26 old subjects and in 56 young ones. The results demonstrate that HLA-B8,DR3-positive young females display significantly higher levels of APA than HLA-B8,DR3-negative ones. Interestingly, the same is true for elderly subjects on the whole with respect to young individuals. These data are consistent with previous findings demonstrating that HLA-B8,DR3-positive subjects (mainly female) as well as old subjects display (also in the absence of any clinical manifestation), multiple immune dysfunctions that may underlie the predisposition to autoimmunity.