Fig. 2.

Lymphoproliferative responses to (a) PPD, (c) TT, (e) PHA and interferon (IFN)-γ concentrations in the supernatants from peripheral blood mononuclear cells stimulated by (b) PPD, (d) TT and (f) PHA in the three groups of patients. The dotted bars indicate the threshold for positivity (SI ≥ 3). Patients who were not vaccinated against tuberculosis were excluded from analysis of responses to PPD. P-value for comparison between three groups shown in the black box was calculated using the Kruskal–Wallis non-parametric test. P-values for comparison between two groups shown with horizontal black bars were calculated with Dunn's multiple comparison test. PPD, purified protein derivative; TT, tetanus toxoid; PHA, phytohaemagglutinin; LPR, lymphoproliferative response; SI, stimulation index; USP, untreated slow progressors; UP, untreated progressors; FS, full viral suppression. *P < 0·05; **P < 0·01; ***P < 0·001.