The ability of HrTNF-α, HrIL-1β, and HrIFN-γ to modulate IL-6 production by cultured human salivary cell line (HSG) was examined. IL-6 activity was measured by the hybridoma growth factor biologic activity. HrTNF-α had a significant dose-dependent effect, whereas HrIL-1β and HrIFN-γ had moderate and minor effects, respectively. Maximal effect (920 units) was noted when cytokines were applied in combination (1000 units HrIFN-γ and 20 units HrTNF-α) and incubated with human salivary gland cells for 72 hr. The same combination of cytokines had also a marked inhibitory effect (70% of control) on human salivary gland cell growth. This is the first report of these concomitant phenomena in a human cell line originating from salivary tissue.