Blocking of homotypic aggregation with antibodies specific for LFA-1α, LFA-1β, or ICAM-1. Human mast cells were cultured in the presence of SCF (100 ng/mL) and IL-6 (80 ng/mL); (A) without, (B) with IL-4 (10 ng/mL). Mouse MoAbs (20 μg/mL) specific for (C) LFA-1α (TS1/22), (D) LFA-1β (TS1/18), (E) ICAM-1 (RR1/1), (F ) VLA-5 (KH/33), or (G) VLA-4 (SG/73) were added to the culture in the presence of SCF, IL-6, and IL-4. The cells were incubated for 5 days. This experiment has been repeated three times with similar results.