Flow-cytometric assessment of in vivo cytokine-producing monocytes in HIV-infected patients.

We have used two-color flow cytometry to study in vivo monocytic cytokine production at the single-cell level in HIV-infected patients. We demonstrated the presence of intracellular IL-1 alpha, IL-1 beta, IL-1ra, and TNF alpha in circulating CD14+ monocytes from HIV-infected patients. The specificity of intracellular staining with anti-cytokine antibodies was demonstrated by the suppression of the fluorescent signal when staining was performed in the presence of recombinant cytokines. We did not detect any specific intracellular staining when anti-IL-4 antibodies were used since monocytes do not produce IL-4. In vivo intracellular cytokine production of IL-1 alpha, IL-1 beta, IL-1ra, and TNF alpha was higher in monocytes from HIV-infected individuals compared to monocytes from healthy controls; however, only the data concerning IL-1 alpha reached statistical significance. Monocytic cytokines are involved in the regulation of HIV gene expression and may participate in the modulation of the Th1/Th2 balance. The ability to follow the production of a wide range of cytokines by circulating monocytes of HIV-infected patients should allow one to better analyze the role of monocytic cytokines in the pathogenesis of HIV disease.