Figure 4. BT-061 addition to T cells co-cultured with serum pre-treated monocytes or to a circulating whole blood system does not induce CD4 down-modulation of T cells.

(A) Monocytes were incubated for 45 min at 37 °C in medium enriched with the indicated percentages of human serum (0.1% red line, 1% green line, 10% blue line and 100% purple line), or in normal medium (black line). Afterwards the monocytes or medium (filled grey) were added to untreated or BT-061 decorated T cells. After 18  h of incubation at 37 °C, CD4 expression was determined cytofluometrically. Data from one experiment with cells derived from two individual donors are shown. (B) Statistical analysis from experiments in (A). Error bars indicate SEM. (C) Fresh human whole blood was set to rotate in surface-heparinized loops and treated with 1 U/mL heparin and additionally with the indicated concentrations of BT-061 (light and dark grey bars) or PMA (0.05 μg/ml)/Ionomycin (0.75 μg/ml) (black bars). The loops were rotating at a speed of 10 rpm. PBMC were isolated from the same donor and treated with the indicated concentrations of BT-061 (light and dark grey bars) or PMA (0.05 μg/ml)/Ionomycin (0.75 μg/ml) (black bars). Following incubation of whole blood and PBMC at 37 °C for 15 min, after 3 or 6 h samples were harvested and CD4 expression was determined cytofluometrically. Statistical analysis for data of 2 experiments with samples derived from 3 donors. Error bars indicate SEM.