Effects of CP on cell subpopulations in the bone marrow at 2, 7, 15 and 24 days after a single i.v. injection determined by three-colour flow cytometry. Lymphocytes and granulocytes were distinguished by FSC/SSC profile. Lymphocytes were gated for further analysis by the expression of IgM and CD90 (b, e, h, k, n) and by IgM and CD45R (c, f, i, l, o). Two B cell populations could be distinguished: pro/pre B cells (IgM− and CD90+) and NF-B cells (IgM+ and CD90+). Lymphocytes were almost completely depleted at 2 days after treatment (d, e, f). The figures were established using all events collected by flow cytometry (40 000) and after gating for lymphocytes based on FSC/SSC profile.