Transgenic IgG expression in vitro. Supernatants of cultured B cells (with cytokines as indicated in each panel) from various transgenic and nontransgenic mice were tested. (A) Transgenic Flag+ IgG2a expression; (B) transgenic IgG1^a expression; and (C) transgenic AD8+ (idiotype+) IgA expression. Each data point represents an independent culture, derived from independent transgenic mice. In this and subsequent figures, the 774 line and 820 line were tested in separate experiments from the 336 line, the 234 line, the 231 line, and the 761 mice, as the latter four mice were established 1 yr later.