"Naturally-occurring" anti-K1: possible association with mycobacterium infection

We report a case of "naturally-occurring" (nonred blood cell stimulated) anti-K1. The patient had never received a blood transfusion. Red blood cell antibody screening panels showed agglutination with K:1 red blood cells at room temperature and not in the anti-globulin test. Testing with 2-mercaptoethanol showed the antibody to be IgM. The antibody is "naturally-occurring" and may be associated with pulmonary tuberculosis.