FIG. 6.

Blockage of CD134 or CD154 inhibits Ig-SC development and Ig production. (A) Splenic cell suspensions (unlabeled or labeled with CFSE) were depleted of CD138⁺ cells and cultured for 7 days with 2 μg/ml ConA plus 1 μg/ml CT in the presence of αCD134L, αCD154, αCD134 plus αCD154, or an appropriate isotype control Ab. Frequencies of cells expressing the B220^low, CD138⁺ phenotype were determined and are given as percentages. (B) Levels of IgA, IgM, and IgG secreted into culture supernatants were determined by ELISA. (C) Frequencies of dividing CD19⁺ cells in cultures treated with αCD154 or control Ab were analyzed by FACS at day 4 of culture and are given as percentages (means ± standard deviations). Representative data from three independent experiments are shown. and , significant differences at P values of ≤0.01 and ≤0.001, respectively, compared to the αCD134L and αCD154 controls.