This project aimed to investigate the ability of clinical isolates of Candida albicans to differentially induce members of the IL-12 cytokine family thereby potentially influencing the immune response of the host.
Methods: Human monocytes from an immortalised cell line (THP-1; from a patient with acute monocytic leukaemia) were stimulated (0, 2, 6 and 24 h) with either Porphyromonas gingivalis lipopolysaccharide or heat killed C. albicans. RT-PCR was then used to detect expression of the mRNA for various proteins of the IL-12 cytokine family.
In addition, heat killed C.albicans strains (5x104, 5x105, 5x106cells /ml) with LPS (100 ng/ml) were added to THP-1 cells for 24 h. The resulting supernatant was then tested for IL-12 family cytokine expression by ELISA.
Results: RT-PCR revealed that C. albicans stimulated THP-1 expression of mRNA for certain IL-12 cytokine family proteins. Furthermore, ELISA demonstrated several IL-12 cytokine family members were induced during cell culture with C. albicans and LPS. Different patterns of IL-12 cytokine production were evident with the test strains. A concentration-dependent response was also seen for two strains of C albicans for IL-23 production.
Conclusions: This study showed that C. albicans strains differ in their ability to induce IL-12 cytokine family secretion by THP-1 cells. Extrapolation of these findings to the host could indicate that strain-dependent immune responses are triggered by C. albicans which might influence whether infection, clearance or colonisation of the organism occurs.