This work investigated whether interleukin 1 beta (IL-1 beta) release from epithelial cells is modulated by antigen challenge in vivo, and inflammatory cells in vitro. Bronchial epithelial cells were obtained before and after segmental allergen challenge in allergic and normal individuals, and were cultured with and without autologous bronchoalveolar lavage (BAL) cells. IL-1 beta in culture medium was quantitated by enzyme-linked immunoabsorbent assay (ELISA). Pre-challenge IL-1 beta levels from epithelial cells were similar in allergic (4.4 +/- 0.8 pg/ml, n = 32) and normal (6.8 +/- 1.7 pg/ml, n = 17) subjects. IL-1 beta levels were significantly elevated from epithelium with BAL cell co-culture vs without co-culture in both subject groups (allergic, 13.2 +/- 2.3 pg/ml, P = 0.006; normal: 16.4 +/- 4.0 pg/ml, P = 0.007). Post-challenge IL-1 beta from epithelial cells without BAL cells was increased in both groups, but significant only for allergic subjects (P = 0.003). Post-challenge IL-1 beta from epithelial with BAL cells changed little for allergic subjects (13.8 +/- 2.4 pg/ml), and increased for normal subjects (20.0 +/- 4.8 pg/ml). Decreased production of tumour necrosis factor alpha (TNF-alpha) was observed in allergic subjects (day 1: 447 pg/ml vs day 2: 258 pg/ml). Moreover, pre-challenge release of TNF-alpha and IL-1 beta levels from epithelial + BAL cells correlated well for allergic (r = 0.84) and normal subjects (r = 0.6), but post-challenge release correlated only in normal subjects (r = 0.90). These results indicate that bronchial epithelial cells and BAL cells interact, modulating release of these inflammatory cytokines.