Fig. 4.
Measurement of cytotoxic activities of supernatants of cultures of type II and III clones against L929 cells. Serially diluted supernatants of 4-day cultures of 5 CD4+ clones after stimulation of 30 Gy irradiated allogeneic PBLs having DRB1*1502 in the presence of 20 U/mL rIL-2 (initial cell concentration of 2 × 105 cells/mL) or control medium containing 20 U/mL rIL-2 were incubated with monolayer L929 cells in the presence of 1 μg/mL actinomycin D for 18 hours, after which the viable cells were stained with methylene blue and the absorbance at 660 nm was measured.
