SECRETORY IMMUNITY IN HIV-INFECTION

Secretory IgA plays a crucial role in the defense of pathogens at muco sal surfaces. As CD4+ T cells are lost early in the mucosa of human im munodeficiency virus (HIV)-infected patients and as CD4+ T cells play an essential role in the regulation of specific IgA responses to patho genic agents at mucosal sides, it could be expected that this first li ne of defense is impaired in HIV-infected patients. Therefore, several studies were undertaken to characterize the humoral immune response a t mucosal surfaces. However, the results obtained so far are in part c ontradictory. For intestinal IgA, reduced, increased and no changes co mpared to controls were described. The different results may be due to different methods applied. In most studies an abnormal predominance o f HIV-specific IgG over IgA response was found in the intestine of HIV -infected patients. Studies on cytomegalovirus-specific intestinal ant ibodies indicate a complete lack of a specific intestinal IgA response . However, in cryptosporidiosis of HIV-infected patients, diarrhea per sists despite a secretory IgA response indicating that other factors a re also important for the clearance of this pathogen.