CD40L expression by activated PBMC, T-cell lines, and CD4⁺ T-cell clones. After stimulation with ionomycin and PMA for 8 hours (PBMC) or 4 hours (T-cell lines and CD4⁺T-cell clones), immunostaining of cells was performed using MoAb 106 or bCD40-Ig. The immunostaining with MoAb 106 or bCD40-Ig is shown by a bold line and the immunostaining with isotype-matched control reagent is indicated by a thin line. The fluorescence intensity is expressed on the abscissa on a log scale and the number of events is expressed on the ordinate. (A and B) Activated PBMC from a normal control; (C) PBMC from a normal control without activation; (D and E) activated PBMC from patient AM (family 19) with the splice site mutation in exon 3 (nt 367G → A); (F and G) activated PBMC from a CVI patient with confirmed normal CD40L sequence; (H, I, and K) patient TA (family 7) with the missense mutation T254M and includes activated PBMC (H), an activated T-cell line (I), and an activated CD4⁺ T-cell clone (K).