Figure 1.

Mycobacterium tuberculosis H37Ra (Mtb)-immunised Lewis (LEW) rats showed the highest level of tumour necrosis factor (TNF)α secretion during the Rec phase of adjuvant arthritis (AA), but Wistar-Kyoto (WKY) rats displayed an opposite profile. LEW (△) (n = 4 each) and WKY (▲) (n = 3 each) rats were killed at different time points after Mtb injection and their draining lymph node cells (LNC) were harvested. These LNC were cultured for 48 h in a 96-well plate with or without the addition of any exogenous antigen. The supernates were then collected and analysed for TNFα by enzyme-linked immunosorbent assay (ELISA). The LNC/culture supernates of individual rats were tested separately and then the results of each of the two subgroups (LEW/WKY) were presented as pg/ml (mean ± SEM). For comparison, medium background was subtracted from antigen-induced cytokine (Δ pg/ml). *p < 0.05 and **p ≤ 0.025, when levels of a particular cytokine at other phases of AA were compared with that at Inc phase for the same rat strain (LEW/WKY); +, p ≤ 0.05, and ++, p ≤ 0.025, when cytokine levels were compared between LEW and WKY rats at the corresponding phase of AA. Inc = incubation phase; Ons = onset phase; Pk = peak phase; and Rec = recovery phase. Testing of additional animals following the above protocol yielded similar results.