Anti-C as a naturally-occurring antibody.

IT IS accepted generally that antibodies directed against red blood cell antigens in the Rh system result from isoimmunization either by transfusion or pregnancy and rarely can be considered “naturally-occurring.” Diamond et al. reported the first example of a naturally-occurring antibody within this system in 1942.3 They described an antibody, apparently anti-D, in the serum of a five-year-old Rh-negative boy who had no history of prior transfusion. Naturally-occurring anti-D is extremely rare,9 as there are only three reports of its occurrence in the literature.’, 3, 5 Naturally-occurring anti-E is somewhat more common. Race and Sanger,ll Dunsford.4 Jenkins,’ and Grove-Rasmussen and Levine,s have reported examples of sera containing anti-E in patients with no history of appropriate antigenic stimuli. Other described specificities of such antibodies in this system include two examples of anti-Cw 2. 8 and one of anti-Cx.10 This report recounts another example of a “naturally-occurring” Rhesus antibodythe hitherto unreported specificity of anti-C (anti-rh’) .