IF staining histograms of EBV B-cell lines incubated with TUGh4 antibody (solid tracings) or no first antibody (open tracings), followed by PE-conjugated antirat IgG. B-cell lines were derived from (A) unaffected control and γc-SCID patients with (B) Q188• terminating in exon 4 with no detectable mRNA, (C) R226H hot spot extracellular point mutation in exon 5, and (D) R289• hot spot intracellular truncation mutation in exon 7.