(A) Cytokine production by stromal cells. Supernatant from stromal cells were collected 2 days after media change and assayed by ELISA for the above cytokines. Values are the mean ± SEM of 10 experiments. (B) Induction of B-cell apoptosis by stroma CM and influence of neutralizing antibodies to cytokines. Results are expressed as percentage of apoptotic cells and represent the mean of five experiments.