Peripheral Treg cells are induced during acute FIV infection.

<p>(A) CD4⁺CD25^hi percentages within the PBMC population were determined by flow cytometry on days −12, 0, 7, 14, 35, and 54 post-FIV infection. Percentages were multiplied by lymphocyte absolute number to quantify absolute numbers of CD4⁺CD25^hi cells. Absolute numbers were then expressed as a percentage of day −12 values and averaged. (B) CD4⁺CD25⁺FoxP3⁺ percentages within the PBMC population were determined by flow cytometry, then absolute numbers were expressed as a percentage of day −12 values and averaged. (A, B) Significance was determined relative to day −12 values. * indicates <i>p</i><0.05. (C) FoxP3 mean fluorescence intensity (MFI) within CD4⁺CD25⁺FoxP3⁺ and CD4⁺CD25⁻FoxP3⁺ PBMCs from vehicle control-treated cats was determined by flow cytometry. Levels and kinetics did not significantly differ between treatment groups. (D) FoxP3 and TGF-β MFI within CD4⁺CD25⁺ PBMCs from vehicle control-treated cats was determined by flow cytometry. Levels and kinetics did not significantly differ between treatment groups. (E) Percent of CD4⁺CD25⁺FoxP3⁺ PBMCs expressing CD62L was determined by flow cytometry. (F) Percent CD4⁺Ki67⁺ PBMCs from vehicle control-treated cats was determined by flow cytometry and is compared to CD4⁺CD25⁺FoxP3⁺ PBMC absolute number. Levels and kinetics did not significantly differ between treatment groups. (C–F) Significance was determined relative to day 0 values. * indicates <i>p</i><0.05. (G) Percent of CD4⁺ T cells expressing CD25 and FoxP3 in lymphoid tissues was determined by flow cytometry on days 14, 35, or 54 post-FIV infection. (A–G) Mean ± SEM is shown.