Background and study aim: Interleukin 12 (IL-12) increases T cell proliferation, elevates natural killer (NK) and cytotoxic T cell activity, and induces the production of interferon gamma (IFN-γ).  The aim of this study was to assess the potential relationof serum interleukin 12 levels in the suppression of CD4+ T-cell count in HIV patient in spite of low viral load after Highly Active Anti-Retroviral Therapy (HAART).
Patients and Methods: Thirty sero-positive HIV male patients were selected with low viral load after HAART.  They were divided into two groups according to their immunological response. The first group included 15 male patients with low CD4 counts. The second group included 15 male patients with high CD4 counts. All patients were investigated for complete blood count (CBC), liver function test (LFT), kidney profile (KP), estimation of the levels of TNF-α, IFN-γ, IL-10, IL-12.
Results: Serum levels of IL-12 were significantly higher in Group II than in Group I (mean±SD IL-12 levels of 11.91± 2.8 versus 6.9±2.9, p<0.05). The serum levels of IL-12 were positive correlated with CD4 counts (r = 0.514; p<0.05). Similarly, a positive correlation between IL-12 levels and IFN-γ levels were noted (r=0.Session [CurrentTestPartID]2, p<0.01). No significant correlations were observed between IL-12 levels and viral loads and also, no correlation between serum levels of IL-12 and serum levels of IL-10 and TNF-α.
Conclusion: Reduction of the levels of IL-12 in immunologic non-responders HIV-infected patients may play a role in impairment of immunological recovery following HAART. Although, we found that IL12 production was correlated with IFN-γ, the mechanism by which the reduced production of IL-12 in immunologic non-responders HIV-1-infected patients remains poorly understood.