FIG. 3.

CD4⁺ T cells in the peripheral blood of RP and CP macaques over the time course of infection. (A) Total CD4⁺ T cells are compared in RP (red) and CP (blue) macaques. (B) Comparison of total CD4⁺ T cells in peripheral blood at the time of euthanasia shows significantly lower total CD4⁺ T-cell counts in CP versus RP macaques (Mann-Whitney U test). Comparison of memory (C) and naive (D) CD4⁺ T cells in the blood of two RP and two CP macaques inoculated with SIVsmE543-3 shows the selective depletion of memory CD4⁺ T cells that occurs in RP macaques, as determined by CD28 and CD95 expression. In contrast, CP macaques demonstrate early depletion of memory CD4⁺ T cells with partial replenishment but subsequent progressive loss of both memory and naive CD4⁺ T-cell subsets during long-term progression.