Immunological aspects of congenital atrioventricular block

Isolated congenital heart block (CHB) in children is strongly associated with the occurrence of autoantibodies to Ro/SS-A and La/SS-B in the circulation of the mother. Although these antibodies are generally found in patients with generalized autoimmune diseases, they may also occur in symptomless mothers of CHB patients. It is thought that anti-Ro/SS-A and anti-La/SS-B may reach the fetal circulation via transplacental transport, starting around the 20th week of gestation. Although several hypotheses have been put forward, the exact mechanism through which these autoantibodies bind the fetal conduction system and elicit a local inflammatory response is still unclear. Also, the induction of the autoantibody response in the mother remains largely obscure, although a putative role of viral infection has been suggested. In this overview, the structure of the involved antigens will be discussed, followed by the nature of the antibodies. Recent data regarding the etiology of the anti-Ro/SS-A and anti-La/SS-B response and the role of these autoantibodies in the pathogenesis of CHB will be presented.