Inhibition of proteolytic cleavage of perforin in the patient with CAEBV. Stimulated PBMCs were cultured in the presence (+) or absence (–) of 200 nM concanamycin A (CMA) for 5 hours. Lysates were prepared from the cells and perforin was detected by immunoblotting with 2d4-perf antibody under nonreducing conditions.^29,30  Two bands corresponding to perforin are seen. The upper (U) and lower (L) bands indicate precursor and mature form of perforin, respectively. Protein concentrations were equal in each sample. The right panel indicates a darker exposure from a repeat experiment using the father's cells.