Expression of CD40L on CD4T 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 CD8T 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 CD4T 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 CD4T cells and central memory CD4T 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 CD4T cells is higher in individuals in remission compared to those with active HIV-associated KS.