In vivo tumour necrosis factor (TNF)α treatment resulted in decreased interferon (IFN)-γ secretion by B177-restimulated LNC without affecting their proliferative response. LEW rats were treated with PBS (□) or TNFα () as described in the legend to Figure 2, with the exception that one subgroup of rats was immunised with Mycobacterium tuberculosis H37Ra (Mtb) (a, c, e), whereas the other was injected with HEL/IFA (b, d, f). At day 9 after injection with Mtb or HEL, the draining LNC of these rats were harvested and tested in a proliferation assay ((a, b); n = 8 each). Peptide 333 to 347 of Bhsp65 (B333), peptide 65 to 78 of HEL (HEL65), and native HEL were used as control peptide/protein antigens. The results are presented as mean stimulation index (SI) ± SEM. In addition, the supernates collected after 72 h of culture of LNC of Mtb- or HEL-immunised rats were tested by ELISA for IFN-γ (c, d) and interleukin (IL)-10 (e, f) (n = 5 each). The results of cytokine analysis are shown as Δ pg/ml (mean ± SEM). *, p < 0.05 and **, p ≤ 0.025, when compared with the respective PBS control.