Dynamics of CD43 and moesin during cell aggregation. (i) T lymphoblasts adhered to FN80 were treated with the proaggregatory anti-CD43 HP2/21 MoAb. Time-lapse videomicroscopy analysis was then performed as described in the Materials and Methods. Sequential time frames are shown. White arrowheads point to uropods of cells participating in the formation of small and large aggregates. (ii) T lymphoblast aggregation was induced by using the anti-CD43 HP2/21 MoAb, and upon cell incubation at 37°C for 5 (A), 10 (B), and 30 (C) minutes, cells were fixed and stained for CD43. (iii) Similarly, 5 (A) and 30 (B) minutes after the triggering of cell aggregation with the anti-CD43 HP2/21 MoAb, cells were fixed and stained for moesin by using the biotinylated antimoesin 38/87 MoAb. The same cells were photographed under epifluorescent (above) and bright field (below) conditions. Arrows point to cellular uropods.