ABNORMAL MIXED LYMPHOCYTE REACTIONS IN THE FAMILY OF A PATIENT WITH SEVERE COMBINED IMMUNODEFICIENCY

Abstract

SUMMARY The mixed lymphocyte culture (MLC) test was performed in the parental families of a child with severe combined immunodeficiency disease (CID). The investigation revealed several instances of nonresponse in the MLC test in spite of HL-A nonidentity. The abnormal MLC nonresponses were not associated with any single HL-A haplotype or with the occurrence of lymphocytotoxic or blocking antibodies. Immunogenetically the findings might be explained as a coincidence by chance of identities on the MLC locus among the subjects studied. The MLC anomalies were found also when lymphocytes of paternal family members were tested against lymphocytes from the maternal family. Of particular interest was that maternal lymphocytes did not respond to paternal cells. This observation suggests that, at least in this family, the carrier state of CID might be recognizable by failure of normal stimulation in MLC. Furthermore, the mother's and two maternal uncles' lymphocytes were nonresponsive when tested against the patient's cells. This raises the possibility of an HL-A-nonidentical, MLC-identical bone marrow donor when an HL-A-identical sibling is not available.