IL-2 mRNA is decreased in CD8+ lymphocyte targets following CD4+CD25+ co-culture. CD8+ lymphocytes from FIV- or FIV+ cats were either untreated, ConA stimulated (5 ug/ml), or CD8+ targets were ConA stimulated for two hours prior to autologous CD4+CD25+ Treg co-culture. After twenty-four hours, RNA was isolated and reverse transcription RT PCR was performed on all sample groups. For the CD8+/CD4+CD25+ co-culture, CD4+CD25+ cells were depleted by FACS prior to RNA isolation. IL-2 mRNA was decreased by approximately four-fold in ConA stimulated, CD8+ lymphocytes from FIV+ cats following CD4+CD25+ co-culture (p < 0.05, arrows). Each bar represents the mean + SEM for six experiments.