Gamma-IFN induces a differential expression of HLA-DR, DQ and DP antigens on peripheral blood myeloid leukemic blasts at various stages of differentiation.

Using specific monoclonal antibodies and the indirect immunofluorescence technique, peripheral blood myeloid leukemic blasts from 49 patients were studied for DR expression, 42 for DQ and nine for DP after four days of culture without and with gamma-IFN. The expression of class II molecules on untreated cells depended upon the stage of differentiation and was maximal for DR antigens and lower for DP, while DQ was present only in a small percentage of M2, M4 or M5 blasts. M3 blasts lacked both DR and DQ. Maximal increase of surface expression induced by gamma-IFN was observed for DR molecules independently from the differentiation stage. No significant modification was seen for DQ. Preliminary data concerning DP indicate an increased expression in some of the tested samples. Thus the results obtained on peripheral blood blasts parallel previous observations on leukemic cell lines.

[Phagocytic activity and cytochemical characterization of acute human myeloblastic leukemia cells]. / Attività fagocitaria e caratteristiche citochimiche in cellule di leucemie acute umane mieloblastiche.

The ability of leukemic cells to phagocytize in vitro inert latex particles was tested in a group of non-lymphoblastic acute leukemia causes classified according to the FAB criteria. Promyelocytic, myelomonocytic, and myeloblastic leukemias were found to possess the highest percentage of cells with phagocytic activity. The cytochemical characterization of the cells revealed that the majority of phagocytic elements were negative for alpha-naphtyl acetate staining and positive for the peroxidase reaction. These unexpected findings could be explained by the impaired differentiation process of leukemic cells.