Lck activity in CD4 T cells from ICL patients. Peripheral blood CD4 T cells from healthy control subjects (C) and ICL patients (P1, P2, P3) were incubated with (+) or without (−) a plate-bound anti-CD3 Ab for 5 minutes and lysed. Lysates were immunoprecipitated with a rabbit polyclonal anti-Lck Ab. Lck immunoprecipitates were incubated with [³²P]γ-ATP, cold ATP and the tyrosine kinase substrate–enolase. Reactions were run on polyacrylamide gels, transferred to PVDF membranes, and exposed to radiosensitive films. Bands on radiography images represent autophosphorylated Lck (phospho-Lck) and phosphorylated enolase (phospho-enolase). Membranes were subsequently Western blotted (WB) with a mouse monoclonal anti-Lck Ab. Each radiography image and a corresponding blot is representative of 3 experiments.