JMH VARIANTS - SEROLOGIC, CLINICAL, AND BIOCHEMICAL ANALYSES IN 2 CASES

Background: JMH is a high-frequency red cell blood group antigen that resides on a 76- to 80-kDa glycosylphosphatidylinositol-linked protein also known as CDw108. Antibodies with JMH specificity are often autoi mmune and are usually, if not always, clinically benign. Some individu als with JMH-variant antigen produce alloantibodies to JMH, but little evidence concerning their clinical significance is available. This ar ticle reports on two patients who express a JMH-variant antigen and pr oduced alloanti-JMH. Study Design and Methods: Murine monoclonal antib odies and human antibodies to JMH were used in hemagglutination, radio immunoassay, and Western blot testing of red cells from two JMH-varian t patients; antiserum from one of these patients was also used in bioc hemical studies. In addition, in vivo survival of JMH-positive red cel ls was studied in the same patient. Results: Biochemically, both examp les of red cells with the JMH-variant phenotype expressed a JMH protei n with a molecular weight similar to that of the normal JMH protein. F or both patients, family studies suggested an autosomal recessive patt ern of inheritance. Survival study demonstrated reduced in vivo red ce ll survival in one patient, Conclusion: JMH-variant phenotypes express a protein of normal molecular weight and are inherited in an autosoma l recessive pattern. Furthermore, individuals with this phenotype can produce clinically significant antibodies.