concanavalin-a and cycloprodigiosin

Two types of immunosuppressants, cycloprodigiosin hydrochloride (cPrG) and L-leucyl-L-leucine methyl ester (LeuLeuOMe), both have the ability to selectively inhibit the lysosomal function, and a related compound to cPrG, prodigiosin 25-C, and LeuLeuOMe have been reported to selectively inhibit the T cell function in vitro. We therefore examined the cell-type specificity of cPrG and LeuLeuOMe using murine splenocytes. Concanavalin A (Con A)- and lentil lectin-induced proliferation was suppressed by cPrG more profoundly than lipopolysaccharide-induced proliferation. At the optimal concentration, Con A induced the proliferation of both CD4+ and CD8+ cells, whereas at a supra-optimal concentration Con A induced rather selective proliferation of CD8+ cells. Irrespective of the dose of Con A, CD4+ and CD8+ cells were equally affected by cPrG. In contrast, LeuLeuOMe induced the selective loss of CD8+ cells. cPrG enhanced the apoptosis of murine splenocytes and nylon fiber column-purified T cells cultured in the presence of Con A, as shown by the decrease in cell size and/or DNA fragmentation. Overall, this study revealed that the cell-type specificity of cPrG is different from that of LeuLeuOMe, and that the immunosuppression by cPrG is associated with apoptosis.

Topics: Animals; Apoptosis; CD4-CD8 Ratio; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Concanavalin A; Flow Cytometry; Immunosuppressive Agents; Indoles; Lipopolysaccharides; Lymphocyte Activation; Male; Mice; Mice, Inbred BALB C; Pyrroles; Spleen; T-Lymphocytes

Cycloprodigiosin hydrochloride (cPrG.HCl), a member of the prodigiosin family, is a red pigment obtained from the marine bacterium Pseudoalteromonas denitrificans. cPrG.HCl markedly suppressed 3H-thymidine incorporation by concanavalin A stimulated murine splenocytes but had little effect on lipopolysaccharide dependent 3H-thymidine incorporation, indicating that cPrG.HCl acts as a selective inhibitor of T cell proliferation in the same way as other members of the prodigiosin family. cPrG.HCl inhibited the proliferation of the PMA stimulated Jurkat cells through an apoptotic process. Intriguingly, cPrG.HCl inhibited the H+ translocation by vacuolar type ATPase in chromaffin granule membranes without any effect on either its ATPase activity nor on the membrane conductance of phospholipid bilayers, suggesting that cPrG.HCl selectively uncouples H+ translocation from the ATPase reaction rather than acting as a non-specific ionophore. Since crystalline cPrG.HCl is highly stable, it raises the possibility of its therapeutic use as an immunosuppressant.

Topics: Animals; Apoptosis; Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; Cell Division; Chromaffin Granules; Concanavalin A; DNA; Enzyme Inhibitors; Gram-Negative Aerobic Bacteria; Humans; Immunosuppressive Agents; Indoles; Intracellular Membranes; Jurkat Cells; Lipopolysaccharides; Lymphocyte Activation; Mice; Proton-Translocating ATPases; Pyrroles; Seawater; Spectrometry, Mass, Secondary Ion; Spleen; T-Lymphocytes; Thymidine; Vacuolar Proton-Translocating ATPases