The Development of Large Immature Mononuclear Cells in Mixed Leukocyte Cultures.

By B .iw ui BAIN, MAGDALENE R. VAS AND LoUIS LOWENSTEIN W HEN human peripheral blood leukocytes are cultured in vitro in the presence of phytohemagglutinin, some of the cells transform into immature forms that are capable of mitotic division.’ An incidental observation by Schrek and Donnelly2 indicated that, under certain conditions, a similar reaction might occur without phytohemagglutinin. These authors were studylug the morphology and motility of lymphocytes from 20 leukemic and nonleukemic patients, using the slide-chamber method and time-lapse cinematography. In one of their cultures, after 5 days’ incubation, they observed “a small number of large cells with large clear nuclei and prominent nucleoli.” A few of the cells were in mitosis. The authors noted that the culture “proved to be a mixture of bloods from 2 patients with hemochromatosis,” but did not elaborate on this observation. Since this one culture differed from the others only in that it was a mixture of leukocytes obtained from two subjects, it seemed desirable to us to determine whether the large cells would appear consistently when leukocytes from two normal individuals were mixed together and cultured in the absence of phytohemagglutinin.