COSTIMULATION OF HUMAN CD4(-CELLS WITH LFA-3 AND B7 INDUCE DISTINCT EFFECTS ON AP-1 AND NF-KAPPA-B TRANSCRIPTION FACTORS() T)

We have earlier shown that stimulation of human CD4(+) T cells with SE A presented on Chinese hamster ovary (CHO)-DR transfectants coexpressi ng either B7 or LFA-3 resulted in distinct cytokine profiles. We now d emonstrate that B7, but not LFA-3, strongly costimulated IL-2 transcri ption and mRNA expression in CD4(+) T cells. Maximal increase in IL-2 transcription was recorded with CHO-DR/B7/LFA-3, suggesting a cooperat ive effect of B7 and LFA-3 at the transcriptional level. Gel-shift ana lysis demonstrated that stimulation of CD4(+) T cells with CHO-DR and staphylococcal enterotoxin A was sufficient to induce significant amou nts of NF-kappa B binding proteins, whereas induction of AP-1 binding proteins required costimulation. LFA-3 induced moderate levels of AP-1 , but did not influence the levels of NF-kappa B, while B7 costimulati on strongly induced both AP-1 and substantially enhanced NF-kappa B bi nding proteins, The CHO-DR/B7/LFA-3 triple transfectant induced a furt her increase in AP-1 and NF-kappa B binding proteins compared with the double transfectants. The level of Oct-1 binding proteins remained si milar in all samples. Super-shift analysis revealed that the NF-kappa B complex of costimulated CD4(+) T cells contained large amounts of p5 0, substantial amounts of p65, and marginal levels of c-Rel proteins. The AP-1 binding proteins contained c-Jun, Jun-D, and Fra-1, but margi nal amounts of Jun-B and c-Fos. Our results indicate distinct effects of B7 and LFA-3 costimulation on the activity of AP-1 and NF-kappa B. These may partly account for the differential effects of B7 and LFA-3 costimulation on IL-2 expression.