Background and objective: Sarcoidosis (SA) is a disorder of unknown aetiology. Mycobacterium tuberculosis heat shock proteins (Mtb-hsp) have been considered as causative agents of SA. The role of Mtb-hsp in the immune response in SA has not been investigated.
Methods: Mtb-hsp-stimulated T-cell subsets and Th1/Th2 cytokine patterns in the supernatant from peripheral blood mononuclear cell cultures from 22 SA patients, 20 tuberculosis (TB) patients and 20 healthy volunteers were compared using flow cytometry.
Results: In unstimulated cultures, a significantly higher percentage of CD8(+)alphabeta(+)T-cells were present in SA versus controls. Similarly there was a significantly increased IL-6 and decreased IL-4 level in SA and significantly lower INF-gamma, IL-2, IL-4, IL-10 production in TB versus controls. After Mtb-hsp stimulation, there was a significantly increased TNF-alpha, IL-6, IL-10 and decreased INF-gamma, IL-2, IL-4 production in SA and significantly increased TNF-alpha, IL-6 concentrations in TB versus controls. CD8(+)gammadelta(+)IL-4(+)T-cells were detected significantly less often in Mtb-hsp-induced cultures in SA versus controls. Comparing SA versus TB, CD4(+)gammadelta(+)TCR-cells were significantly increased in Mtb-hsp-induced cultures in TB versus controls and SA. Before stimulation, significantly increased IL-6, IL-10 and decreased IL-4 level in SA versus TB was revealed, whereas Mtb-hsp stimulation caused significantly increased IL-10 and decreased IL-4 concentrations in SA.
Conclusions: After Mtb-hsp stimulation, increased levels of pro-inflammatory cytokines, TNF-alpha and IL-6 were found in sera from SA and TB patients in comparison with healthy controls; SA patients demonstrated the lowest levels of IL-4 and the highest levels of IL-10.