Cells of the Innate and Adaptive Immune Systems in Kaposi's Sarcoma

SARS-CoV-2-Specific T Cell Immunity in HIV-Associated Kaposi Sarcoma Patients in Zambia

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) virus is the cause of coronavirus disease 2019 (COVID-19). It has caused millions of infections and deaths globally over a 2-year period. Some populations including those living with HIV and/or cancer are reported to be at a higher risk of infection and severe disease. HIV infection leads to a depletion of CD4⁺ T cells which impairs cell-mediated immunity and increases the risk of malignancies such as Kaposi sarcoma (KS) and viral infections such as SARS-CoV-2. However, several other factors including level of immunosuppression and chemotherapy may also affect the immune response against SARS-CoV-2. In this study, we investigated factors affecting SARS-CoV-2-specific T cell immunity towards the spike, nucleoprotein, membrane protein, and other open reading frame proteins in individuals with HIV-associated KS. The KS patients were SARS-CoV-2 seropositive with detectable T cell responses, but had no history of symptomatic SARS-CoV-2 infection. We observed that the T cell responses increase from baseline levels during follow-up, with responses towards the NMO peptide pool being statistically significant. Low CD4 counts below 200 cells/μl were associated with lower SARS-CoV-2-specific T cell responses. Cancer chemotherapy and KS T staging did not have a significant effect on the T cell responses.

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.