Figure 4.

The CD45 antibody 4.14 causes the formation of large U937–T-cell clusters. CD45 mAb 4.14 (1/400 dilution) was added to 10⁴ irradiated U937 cells, 2×10⁵ purified T cells and 0·1 μg/ml CD3 mAb (UCHT1) (a). The cells were cultured for approximately 48 hr and then photographed. In (b) the culture conditions were the same but no CD3 mAb was added. Other inhibitory CD45 mAb (see Fig. 3) had the same effect of increasing U937 – T-cell clustering, and this increase was independent of CD45 isotype.