Correlation between p24gag production and T-cell activation. Tissues from 8 to 32 different donors were infected with X4_LAI.04 or R5_SF162, and for each data point the amount of p24gag accumulated in culture medium bathing 54 infected tissue blocks was measured by p24gag ELISA. Matched uninfected tissue blocks were used as controls. T cells of either CD69⁺ or CD25⁺/HLA-DR⁺ phenotype were considered as activated. The graphs represent the linear regression between the fraction of activated T cells in noninfected tissues and the maximal p24gag production in the matched infected tissue. (A) X4_LAI.04 production correlated with CD25⁺/HLA-DR⁺ T cells. (B) R5_SF162 production correlated with CD25⁺/HLA-DR⁺ T cells. (C) X4_LAI.04 production correlated with CD69⁺ T cells. (D) R5_SF162 production correlated with CD69⁺ T cells.