K. Rafiq et al., CYCLOSPORINE-A INCREASES IFN-GAMMA PRODUCTION BY T-CELLS WHEN CO-STIMULATED THROUGH CD28, European Journal of Immunology, 28(5), 1998, pp. 1481-1491
Despite its calcineurin-inhibiting properties, cyclosporin A (CsA) can
not inhibit IL-2 production when T cells are co-stimulated by CD80/CD
86 on the antigen-presenting cells. We studied the in vitro effect of
CsA on IFN-gamma production. Anti-CD3 monoclonal antibody (mAb) was us
ed as the primary stimulus for activation of purified human T cells. A
stimulating anti-CD28 mAb, or CD80 or CD86 on stably transfected P815
cells, provided the cc-stimulatory signal. IL-2 production was hardly
affected by CsA under these stimulating conditions, while IFN-gamma (
at the protein and mRNA level) was markedly stimulated by CsA. The use
of anti-CD3 or phorbol 12-myristate 13-acetate with ionomycin as the
primary stimulus, together with costimulation through either CD28 or C
D2 using transfectants with the appropriate ligands, allowed us to dem
onstrate that the resistance of IFN-gamma production to inhibition by
CsA required both CD3 and CD28 triggering. Inhibition of IL-10 product
ion, and to a lesser degree of IL-4 production, by CD4(+) cells was re
sponsible for the enhancement of IFN-gamma production in the presence
of CsA. In conclusion, IFN-gamma production by CD28-co-stimulated CD4(
+) T cells is resistant to inhibition by CsA and can even be facilitat
ed by CsA as a result of removing a negative regulatory signal which i
s mainly IL-10 mediated. This finding might have implications for immu
nosuppressive strategies based upon the use of CsA.