[Immunogenetics of Horton's disease and of rhizomelic pseudo-polyarthritis].

The etiopathogenesis of temporal arteritis and rhizomelic pseudo-polyarthritis still remains undefined. A genetic predisposition would seem probable in view of epidemiological data (higher frequency in white caucasian races and in certain countries), the existence of rare familial forms (25 families reported), and the significant increase in incidence in unconnected cases with HLA DR4 antigen (6 studies). Environment may intervene as a precipitating factor in the condition and the role of an infectious agent, to account for the seasonal incidence of this disorder and the rare existence of cases in non consanguineous couples, has been suggested but remains unproven. Disordered immune function probably plays an essential role in the creation of the vascular histological lesions characteristic of the condition. The disordered function involves cellular immunity (fall in OK T8. in blood) and especially humoral immunity with the very frequent presence of circulating immune complexes in the serum and deposition of immunoglobulins and complement at arterial wall level.