Surface CD4 density remains constant on lymphocytes of HIV-infected patients in the progression of disease.

In an attempt to question the influence of circulating virus, soluble gp120 or CD4 self-reacting antibodies upon results of CD4+ T-cell immunophenotyping in AIDS patients, five anti-CD4 mAb defining several epitopes of the V1 and V2 domains of the CD4 molecule were used to analyse the epitopic density of CD4 on lymphocytes of seropositive patients taken at stages II, III and IV of HIV infection, according to the Centers for Disease Control (CDC, Atlanta) classification. Our results demonstrate that each CD4 epitopic density measured on circulating lymphocytes remains constant at a mean level of 46,000 epitopes per cell whatever the stage of the disease and whatever the serum p25 concentration. These data provide evidence that antibody accessibility to several CD4 epitopes is not altered by putative interactions between CD4 molecules and circulating virus, soluble gp120 or anti-CD4 autoantibodies. If such binding events, as expected, do occur in vivo, they are of too low a magnitude to influence the immunophenotyping. Furthermore, we show that mAb specific for different epitopes in the V1 and V2 domains of the CD4 molecule can be used interchangeably for the biological followup of the CD4+ cell population in blood samples of HIV-infected patients.