Impaired antigen-presenting capability of monocytes correlated with their decreased expression of HLA-II antigens in patients with myeloid leukemia.

Antigen-presenting capability and expression of HLA-II antigens on peripheral blood monocytes were analyzed by isotope incorporation technique and indirect immunofluorescence assay with monoclonal antibodies Tü 22, Tü 36 and anti-Leu-M2 in patients with acute and chronic myeloid leukemias (AML, CML). All patients (17 AML and 13 CML) demonstrated impaired antigen-presenting capability of monocytes (P < 0.001), when compared with simultaneously studied controls, which were HLA-identical normal siblings of the patients. These patients also showed a markedly decreased proportion of MAC-120- and HLA-DQ-positive monocytes as compared with the controls (P < 0.001), while the percentage of HLA-DR-positive monocytes in the patients was similar to that observed in the controls (P > 0.05). These findings suggested, therefore, that impaired antigen-presenting capability of monocytes correlated with their decreased expression of HLA-DQ in patients with acute and chronic myeloid leukemias.