Additional examples of cold autoagglutinins with M specificity.

Examples of both anti-M and anti-N have been reported in patients possessing these antigens; however, in only two instances has anti-M been reported as an autoantibody. This paper describes two additional patients with auto anti-M. In each case the anti-M was shown to be an autoantibody by absorption and elution studies. Optimum reactivity was obtained at 4 C. Column chromatogaphy and 2-mercaptoethanol reduction indicated that the antibody was an IgM globulin. There was no evidence of autoimmune hemolysis in either of these patients.