Expression of MLR-S in human myeloid, monocytic and erythroid cell differentiation

The present study describes a comparative study of MLR-S of various stages of fresh and cultured normal or leukemic myeloid, monocytic and erythroid cells. "One-way" MLR was performed, using a slightly modified whole blood method. Fresh leukemic myeloblasts from patients with acute myelocytic leukemia or chronic myelocytic leukemia, in blastic crisis possess a strong MLR-S whereas fresh granulocytes from patients with chronic myelocytic leukemia or from healthy subjects possess no MLR-S. Cultured leukemic myeloblasts from KG-1 or ML-1 cell line possess a very strong or a moderate MLR-S, whereas cultured leukemic promyelocytes from HL-60 cell line possess little or no MLR-S. Fresh leukemic erythroblasts or cultured leukemic erythroblasts from K-562 cell line exert a strong MLR-S whereas fresh erythrocytes exert no MLR-S. Cultured monoblasts from HPL-SK-1 or Murray cell line possess a very strong MLR-S whereas fresh monocytes from healthy subjects or from a patient with chronic monocytic leukemia possess a moderate MLR-S. These observations clearly indicate that there is a good correlation between the MLR-S and the cell differentiation stage. Observations in the present study also support the hypothesis that the MLR-S is a differentiation antigen which is completely lost by the terminal stage of myeloid or erythroid cell maturation or partially lost by the terminal stage of monocytic cell maturation.