Objective: To study the changes of Th1/Th2 cytokines in immunocompetent patients with pulmonary cryptococcosis (PC).
Methods: Twenty immunocompetent patients with PC were identified by histopathological examination and enrolled along with the age- and gender-matched healthy controls. The serum concentrations of interferon-γ (IFN-γ), interleukin-4 (IL-4) and interleukin-12 (IL-12) were measured by enzyme linked immunosorbent assay (ELISA). Peripheral blood mononuclear cells (PBMC) in both groups were isolated and incubated with or without recombinant human IL-12 (rhIL-12) for 48 hours, and the concentrations of IFN-γ and IL-4 in the supernatant were measured by ELISA.
Results: (1) Serum IFN-γ levels were significantly decreased in the patients compared with the control group [(14.5 ± 2.7) vs (81.8 ± 9.8) ng/L (t = 6.590, P < 0.01)], while no significant difference was observed in serum IL-12 and IL-4 levels [(2.5 ± 0.5) vs (2.52 ± 0.6) ng/L and (6.9 ± 1.3) vs (7.3 ± 1.5) ng/L, (t = 0.0035 and 0.2136, P > 0.05) ]. (2) The concentrations of IFN-γ and IL-4 in the supernatant of PBMC without rhIL-12 stimulation showed no differences between the 2 groups [(55.7 ± 13.6) vs (51.1 ± 17.5) ng/L and (5.1 ± 0.7) vs (5.0 ± 0.6) ng/L (t = 0.2979 and 0.0325, P > 0.05) ]. (3) Treatment with rhIL-12 stimulated the release of IFN-γ, but the increase in the patients [(4.3 ± 0.5) folds] was less compared with that in the controls [(7.9 ± 1.1) folds] (t = 3.01, P < 0.01) , while IL-4 concentration in the supernatant of PBMC was not increased in both groups[ (0.9 ± 0.4) vs (1.3 ± 0.4) folds (t = 0.7240, P > 0.05) ].
Conclusions: Serum Th1 cytokine (IFN-γ) levels may be dampened in immunocompetent patients with PC, without significant change in serum levels of Th2 cytokines (IL-4). Deficiency in the response to IL-12 stimulation of Th1 cells may be one of the underlying mechanisms for the decline in serum IFN-γ levels.