The hemolytic uremic syndrome, immunofluorescence studies with positive

Two infants with the hemolytic uremic syndrome are presented. Immunofluorescence studies were done on renal biopsies of each patient as well as on autopsy tissue of one of the patients who subsequently died. In contrast to previously reported immunofluorescence studies in HUS in which only fibrinogen localization was observed, intense localization of antihuman IgM and [31C globulin were observed in glomeruli and in renal arterioles. Similar localization of antihuman IgM, ~ 1C globulin, and fibrinogen was observed in dermal vessels of one of the infants. (Reasons for the discrepancy of these positive findings with those reported by others are discussed.) The present observations suggest that at least in some eases the pathogenesis of HUS may involve humoral immune mechanisms rather than a nonimmune Shwartzman type of coagulopathy.