Chronic myelocytic leukaemia: HLA association and decreased erythrocyte C3b receptor expression.

A series of 27 adult patients with chronic myelocytic leukaemia (CML) were examined for erythrocyte C3b receptor (EC3bR) expression. Twenty-five patients were successfully HLA typed and there was a positive association of CML with HLA-B40 (P less than 0.01). Only 10 (37%) of the patients were EC3bR positive (P less than 0.00001) compared to 223 healthy controls of whom 198 (89%) were EC3bR positive. The positivity of EC3bR and HLA-B40 occurred simultaneously in six patients (P less than 0.05). HLA-B40 positivity and EC3bR expression were correlated with the following variables: age at the time of CML diagnoses, duration of CML (until death or the end of follow-up period 1 July 1983), the stage of CML and simultaneous medication. EC3bR positive patients were significantly more often in remission (P less than 0.05) and also had shorter duration of the disease (P less than 0.005) then did EC3bR negative ones. No significant correlation existed between EC3bR status and the other parameters. The presence of HLA-B40 did not associate with any of the listed variables. These findings may indicate the loss of the receptor in the course of CML with increasing immaturity of cells released from bone marrow.