Effect of activated CD8+ T cell supernatants on Ig expression in vitro antibody synthesis. A representative example of 3 separate experiments is shown. T cells (5 × 105) were stimulated for 18 h with various stimulants either individually or in combination (CD3/CD28, anti-CD3 and anti-CD28; E, estrogen, (10-8 M and 10-9 M), Fas-Fc (μg/ml: 0.75 and 1.25). The culture supernatants from activated CD8+ T cells were collected and added (200 μl) to 1.5 × 106 splenocytes (800 μl) and incubated for 10 days. The culture supernatants were assayed for various immunoglobulin isotypes using ELISA. Graphs represent mean absorbance of triplicates at 405 nm ± SD.