Immunotherapy with anti-IL-6 suppressed in vitro lymph node cell responses to mitogens. DBA/1 LacJ mice were dosed IP with anti-IL-6 antibody (1 mg or 5 mg/week) or irrelevant control antibody (1 mg/week) two days prior to injection with collagen and weekly IP for 10 weeks. Lymph nodes were harvested at the end of the study and isolated lymphocytes cultured with ConA or LPS for 3 days. Cell proliferation was measured using MTT. Bars represent mean ± SEM OD590 as measured in the assay. There was a significant difference (p < 0.05) between the control mAb and both anti-IL-6 mAb doses for both ConA and LPS mitogens. Statistical differences between the groups were determined using ANOVA (SPSS Inc, Chicago, IL).