Diseases like cytomegalovirus (CMV) retinitis, keratoconjunctival sicca, retinal and conjunctival microvasculopathy occur commonly when the CD4 cells count falls below 100 cells/mm3 and Kaposi’s sarcoma occurs when the CD4+T cells count falls below 500 cells/mm3[8]. Here, CD4 is linked to Kaposi's sarcoma.