Figure 5.

Tight aggregation of Raji B lymphoma cells by anti-HLA-DR (L243). (A) Control cells, which form some loose clusters that can be readily dispersed by pipetting (without loss of viability). Note that there are also many single cells (× 10 objective, phase contrast). (B) Cells incubated overnight with L243 at 30 μg ml⁻¹. The cells form large, irregular clusters and there are very few single cells. The cell density seems greater than in (A) because all of the cells in the well are clustered into the centre of the well (× 10 objective, brightfield). (C) A higher-power photograph of the same cells as shown in (B) to better display the tightly aggregated cells (× 40 objective, brightfield). Bar= 200 μM.