Expression of CD40L on CD4+T cells distinguishes active versus inactive HIV-associated Kaposi's Sarcoma.

Kaposi's sarcoma (KS) is a malignancy of vascular origin. It is caused by the Kaposi's sarcoma-associated herpes virus (KSHV). Immune dysregulation is a key feature in the development and progression of KS. The main aim of this study was to determine and compare circulating CD4+ and CD8+T cell subsets including their expression of CD40 ligand (CD40L) and programmed cell death protein 1 (PD1), natural killer (NK) cells, and NK T cells between individuals with active HIV-associated KS versus those in remission. We found that the proportion of CD4+T cells was significantly higher in individuals in remission compared to those with active KS (26.3% vs 13.9%; p = 0.01). We also observed that the proportion of CD4+T cells and central memory CD4+T cells expressing CD40L was significantly higher in individuals with active KS versus those in remission, (10.6% vs 5.4%; p = 0.03) and (14.8% vs 5.9%; p = 0.01) respectively. There was no significant difference in proportion of CD4+ and CD8+ naïve, central memory, effector memory, and terminal effector cells between the two groups. In addition, there was no difference in expression of PD1 on the T cell subsets between the two groups. Furthermore, the proportion of NK cells and NK T cells were not differential between individuals with active disease versus those in remission. CD40L expression is higher in individuals with active HIV-associated KS compared to those in remission. The proportion of CD4+T cells is higher in individuals in remission compared to those with active HIV-associated KS.