ATRA and 9-cis-RA induces IL-4 and IL-5 and inhibits IFN-γ expression by anti-CD3 mAb-stimulated human T cells and PBMC. IL-4, IL-5 and IFN-(levels were quantitated by ELISA in the culture supernatants of anti-CD3 mAb (200 ng/ml)-activated human T cells [circles} or PBMC [inverted triangles] (2.5 × 106/ml) treated with either ATRA (filled symbol) or 9-cis-RA (open symbol). The results are expressed as fold change over vehicle control treated cells. The results shown here are the pooled data from 4 separate experiments using different PBMC donors. It should also be noted that the vehicle controls did not alter the expression of any of the cytokines in these cultures. A paired T test was performed on the combined values from each donor as described in the Methods. *P < 0.05.