Fig. 6. Effects of PRL on short-term cultures of purified mouse B-cell precursors. BM pro-B cells were purified by a two-step separation protocol with immunomagnetic beads, which included negative selection of IgM+ and Mac-1+ cells, and positive recovery of CD43+ cells, most of them B220+ (Day 0 contour plot of B). The titrated doses of PRL shown in the figure were added to the cultures at day 0, and the induced changes were analyzed 4 days later. A, absolute cell recoveries after 4 days of culture were quantified after Trypan blue exclusion (mean of three independent cell cultures; bars, SD; *, samples significantly different from the first column, which represents cell cultures without added PRL; P < 0.05). B, display of cell populations at the startpoint and 4 days later (contour plots and histograms). The absolute cell recoveries shown in the right column histograms were calculated from the relative cell numbers obtained by flow cytometry (inside the displayed windows of the contour plots and the positive cells of the histograms) and the total cell recovery/well of one representative experiment.