title: The effects of nitrogen mustards on the proliferative and Ig synthetic response of human peripheral blood lymphocytes.
abstract: Maximal inhibition of pokeweed mitogen-stimulated Ig production and [3H]thymidine incorporation was shown to occur when unfractionated human peripheral blood mononuclear cells were cultured with concentrations of the nitrogen mustards melphalan, mechlorethamine or chlorambucil in the 20-100-microM range, whereas concentrations of microsome-activated cyclophosphamide (A-Cy) in the 2-mM range were required for equivalent inhibition. Around 400 microM A-Cy, IgM secretion was not inhibited, but secretion of IgA and IgG was. The [3H]thymidine incorporation of enriched populations of both large and small B and T cells all showed about 20-50-fold greater sensitivity to melphalan than to A-Cy, despite a difference of only 6-fold in alkylating activity between these drugs. Large (250 micron 3) B and T cells were only marginally more sensitive to melphalan and A-Cy than small (210 micron 3) T and B cells. Kinetic studies showed that IgG and IgA secreted by day 7 could be maximally inhibited by melphalan added as late as day 3, and IgM synthesis as late as day 2. In contrast, inhibition of Ig production by A-Cy steadily declined after the first day, especially IgM, which was no longer inhibitable by A-Cy on day 3. Inhibition of cumulative Ig production did not occur when A-Cy or melphalan was added on day 5 or later. Cell recombination experiments performed with drug pulsed and untreated monocytes plus B cells and irradiated T cells showed that inhibition of [3H]thymidine or Ig production was most striking when monocytes + B cells (rather than T cells) were exposed to melphalan in the first 16 h. When A-Cy was used in the first 16 h, inhibition of Ig production was partial and inconsistent, and inhibition of monocytes + B cell or T cell [3H]thymidine incorporation was not evident. We conclude that the nitrogen mustards melphalan and A-Cy can inhibit pokeweed mitogen-stimulated DNA synthesis by human T or B cells and Ig production in vitro, but that their mechanisms of action differ.
mesh_terms: D000328:Adult; D000917:Antibody Formation / Q000187:drug effects*; D003520:Cyclophosphamide / Q000494:pharmacology; D004261:DNA Replication / Q000187:drug effects; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007111:Immunity, Cellular / Q000187:drug effects*; D007700:Kinetics; D008213:Lymphocyte Activation / Q000187:drug effects; D008211:Lymphocyte Cooperation / Q000187:drug effects; D008214:Lymphocytes / Q000187:drug effects*; D008875:Middle Aged; D009588:Nitrogen Mustard Compounds / Q000494:pharmacology*
chemical_list: D009588:Nitrogen Mustard Compounds; D003520:Cyclophosphamide