HEMOPOIETIC PROGENITOR CELLS WITH LIMITED POTENTIAL FOR DIFFERENTIATION - ERYTHROPOIETIC FUNCTION OF MOUSE MARROW LYMPHOCYTES

Filtration of mouse marrow cell suspensions over columns of glass wool increased the frequency of small and medium‐sized lymphocytes (SML) and of erythropoietic progenitor units (EPU) by about the same factor. Identical results were obtained when erythropoiesis was assayed by isotope uptake (59FeCl3 and 125IUdR) or by the spleen‐colony techniques. Transfusion of prospective donor mice with erythrocytes virtually eliminated morphologically recognizable erythroid cells from marrow without affecting the frequency of EPU. Injection of prospective donors with cortisol decreased the frequency of SML in marrow but not that of EPU or erythropoietin‐sensitive cells. However, glass wool filtration of lymphocyte‐poor marrow taken from mice pretreated with cortisol resulted in a similar increase in frequency of residual SML and of EPU. Therefore, it appears that a subpopulation of marrow SML are EPU. Whereas glass wool filtration increased the frequency of erythropoietic progenitor and colony‐forming units, the filtration failed to change the frequency of leukopoietic progenitor or colony‐forming units (assayed in mice hypertransfused with erythrocytes to suppress erythropoiesis). It follows that separate progenitor cells for erythropoiesis and leukopoiesis are present in bone marrow of adult mice, in addition to pluripotent stem cells. Copyright © 1968 Wiley‐Liss, Inc.