Figure 2

Formation of T cell-T cell conjugates. Panel A shows a representative experiment of quantification of cellular contacts between MOLT cells and purified CMRA-labeled CD4 T cells. MOLT cells appear as an unstained population with high forward scatter values (in orange); while CD4 T cells were identified by fluorescent staining and low forward scatter values (in purple). Events displaying bright fluorescence and forward scatter values consistent with MOLT cells were defined as cellular conjugates (in red, gate MOLT-CD4 in the figure). The percentage of CD4 T cells forming conjugates in the absence or the presence of Leu3a, or under continuous shacking condition is shown in each plot. Panel B shows the quantification of cellular conjugates in the presence of the following inhibitors: mAbs against the adhesion molecules ICAM-1 (RM3A5), ICAM-3 (140.11) and LFA-1 (R7.1), coreceptor antagonists AMD3100 and TAK779 (all at 10 μg/ml), gp41 inhibitor C34 (1 μg/ml) or Leu3a (5 μg/ml). Data are Mean ± SD of 3 independent experiments including cells from 3 different donors. Asterisks indicate a significant inhibition in the formation of conjugates in the presence of Leu3a and under shaking conditions.