Upregulation of CD23, ICAM-1, CD80, and LT-α expression on JAK3-deficient B cells in response to CD40 ligation. PBMCs from patient no. 1 obtained pre-BMT or patient no. 5 (left panels), or from controls (right panels), were cultured for 24 hours with medium (A) or with soluble mouse CD40L:CD8 plus rat anti-mouse CD8 (B). Cells were then washed and stained with either CD19-FITC plus CD23-PE MoAbs, with CD19-PE plus ICAM-1-FITC MoAbs (panel 1), with CD19-FITC plus CD80-PE or biotinylated LT-α MoAbs followed by strepavidin-PE (panel 2), or with the appropriate isotype controls. Cells were then analyzed using a FACScalibur flow cytometer. Percentages shown in the upper right quadrant of each dot plot represent the percent of CD23⁺, ICAM-1⁺, CD80⁺, or LT-α⁺ B cells detected.