CD4 and Kaposi's sarcoma: In such a patient with a relatively high CD4 count, the mechanisms that can explain Kaposi’s sarcoma are, on the one hand, the interaction between HIV and HHV-8, and on the other hand, the interaction between HIV proteins (e.g. Tat) and host cell molecules (basic fibroblast growth factor, arginine-glycine-aspartic acid binding integrins).