FIG. 8.

Effect of E2₆₆₁ on Daudi cell proliferation and on RBL-CD81 granule release. (A) Daudi cells seeded at 10⁶ cells/ml were either untreated or incubated with 5A6 at 1 μg/ml, E2₆₆₁ antigen at 5 μg/ml alone or preincubated with MAb H53, H53 alone, or mock antigen for 48 h at 37°C. Viable cell counts were performed after 48 h, and untreated cells were found to proliferate 2.7-fold. (B) RBL-CD81 cells were loaded overnight with [³H]5-HT and incubated with E2₆₆₁ or mock antigen for 10 min. After washing, the cells were incubated with 11/4b (10 μg/ml) and [³H]5-HT release was measured. The results are shown as a percentage of the response to anti-hCD81 MAb 5A6 (10 μg/ml), and the mean values from two independent experiments are shown. The addition of E2₆₆₁ antigen alone had no effect on [³H]5-HT release.