Involvement of P-glycoprotein in the transmembrane transport of interleukin-2 (IL-2), IL-4, and interferon-gamma in normal human T lymphocytes

Abstract

The physiological role of the multidrug resistance P-glycoprotein (P- gp), which is expressed by normal human T lymphocytes, is still largely unknown. To investigate whether or not P-gp is involved in the transport of cytokines, peripheral blood lymphocytes were stimulated with phytohemagglutinin (PHA) in the absence or presence of P-gp inhibitors, and concentrations of cytokines (interleukin-2 [IL-2], IL- 4, IL-6, interferon-gamma [IFN-gamma]) in the supernatants of these cultures were quantitated by enzyme-linked immunosorbent assay. P-gp inhibitors included verapamil (Ver), tamoxifen (Tmx), and the P-gp specific monoclonal antibody UIC2. Release of IL-2 was significantly suppressed by these inhibitors at concentrations that were also effective in blocking efflux of Rhodamine-123 from normal T lymphocytes. IL-2 mRNA expression in lymphocytes was not different between PHA control and the cultures with P-gp inhibitors. Ver and Tmx did not interfere with T-cell activation as determined by CD25 and CD69 expression. In a nonhematological model, the P-gp expressing HCT-8 adenocarcinoma cell line, exogenously added IL-2 was shown to exert an inhibitory effect on P-gp mediated Rhodamine-123 efflux. In addition, transepithelial transport of IL-2 by electrophysiologically tight and polarized HCT-8 monolayers was examined. A time-dependent flux of IL-2 across dense monolayers, which was partially inhibited by Ver, was observed. We also investigated whether or not P-gp inhibitors suppressed release of other cytokines produced by activated T cells (IL- 4, IL-6, IFN-gamma). Release of IL-4 and IFN-gamma was significantly inhibited by Ver, Tmx, and UIC2; however, release of IL-6 remained unaffected. These data show P-gp mediated transmembrane flux of IL-2 in T lymphocytes and HCT-8 cells. We conclude that P-gp participates in the transport of cytokines (IL-2, IL-4, and IFN-gamma) in normal peripheral T lymphocytes.

Tamoxifen alleviates disease severity and decreases double negative T cells in autoimmune MRL‐lpr/lpr mice

“…In addition, TAM did not interfere with T-cell activation as determined by CD25 and CD69 expression in the presence of Con A stimulation in vitro, and the data is similar to that in human T cells. 22 The data here also demonstrated that DN T cells did respond to IL-2-activated activation but poorly to cross-linking anti-CD3 activity or phytohaemagglutinin (PHA) (data not shown). To further understand the effect of TAM on IL-2-activated proliferation of DN T cells, the T cells were pretreated with TAM and then stimulated with IL-2 (1 .…”

Involvement of P-glycoprotein in the release of cytokines from peripheral blood mononuclear cells treated with methotrexate and dexamethasone

“…Raghu et al (1996) showed that treatment of PHA-activated peripheral blood lymphocytes with P-gp specific monoclonal antibodies resulted in a significant reduction of IL-2 levels in cultures. Drach et al (1996) studied the involvement of P-gp in the transmembrane transport of IL-2, IL-4, IL-6 and IFN-in PHA-stimulated T lymphocytes from healthy subjects. It was revealed that the release of IL-2, IL-4 and IFN-was significantly inhibited by P-gp inhibitors (i.e.…”

“…Due to postulated P-gp involvement in the transmembrane transport of endogenous proteins, it is also suggested that it has a potential role in the transport of cytokines (Drach et al 1996;Raghu et al 1996). Nevertheless the role of P-gp in the release of cytokines from cells treated with immunosuppressive drugs has to be elucidated.…”

The impact of cytokines on the expression of drug transporters, cytochrome P450 enzymes and chemokine receptors in human PBMC

“…More recent evidence suggests ABCB1 may confer resistance to apoptosis by interfering with caspase-8 activation (Ruefli et al, 2002). A role in the secretion of cytokines (Vasquez et al, 2005) has also been suggested which may account for its expression on these cells (Drach et al, 1996).…”