Effect of verapamil on the IL-2 binding to its active receptor and on the release of IL-2 receptor by activated PBMC.
In the present study we have examined the effect of a Ca2+ channel blocker (verapamil) on the binding of IL-2 to its biologically active receptor (IL-2R), as well as on the release of its soluble form (sIL-2R) by peripheral blood mononuclear cells (PBMC) stimulated by a variety of stimuli. In the same culture systems, cyclosporine A (CsA) was also used as an additional dissecting tool. PHA and the Ca2+ ionophore A23187 enhanced both the percentage of PBMC binding phycoerythrin-conjugated IL-2 (PE-IL-2) and the mean fluorescence intensity of this binding. A phorbol-ester (PMA), on the other hand, enhanced only slightly the proportion of PE-IL-2 binding cells. The two stimulatory combinations (PHA/PMA and A23187/PMA) also up-regulated the proportion of PE-IL-2 binding cells and the fluorescence intensity; the PHA/PMA combination was the most potent of all stimuli used. These two stimulatory combinations, and PHA alone, were also associated with maximal in vitro release of sIL-2R. Verapamil significantly down-regulated PE-IL-2 binding in all culture systems and it convincingly inhibited the release of sIL-2R. Furthermore, this mode of action of verapamil was concentration-dependent. CsA, on the other hand, inhibited the binding of PE-IL-2 to all stimulant-activated PBMC and had only a slight inhibitory effect on the in vitro release of sIL-2R. Our results indicate that there is a correlation between the binding of IL-2 to biologically active receptors on the surface of stimulant-activated PBMC and the release of the soluble form of IL-2R by the same cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Mikhail
N
N
University Diagnostic Laboratories, UMDNJ Robert Wood Johnson Medical School, Piscataway 08854.
Raska
K
K
Raskova
J
J
Degiannis
D
D
D001665:Binding Sites; D000001:Calcimycin / Q000494:pharmacology; D002478:Cells, Cultured; D016572:Cyclosporine / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000187:drug effects* / Q000276:immunology; D010835:Phytohemagglutinins / Q000494:pharmacology; D015375:Receptors, Interleukin-2 / Q000187:drug effects* / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology*
D007376:Interleukin-2; D010835:Phytohemagglutinins; D015375:Receptors, Interleukin-2; D000001:Calcimycin; D016572:Cyclosporine; D014700:Verapamil; D013755:Tetradecanoylphorbol Acetate