Cell-type–restricted expression of GzmB. (A) Purified granulocytes, basophils (B), eosinophils (E), and neutrophils (N) were cultured overnight in medium alone or with IL-3 (10 ng/mL), IL-5 (50 ng/mL), and GM-CSF (50 ng/mL) as indicated. The GzmB content in total cell lysates was determined by specific ELISA. Mean values of triplicates of a representative experiment out of 3 are shown. (B) Protein extracts derived from freshly isolated cells or from cells cultured for 24 hours in medium alone or with IL-3, IL-5, and GM-CSF (all at 50 ng/mL) were analyzed for GzmB and Pim-1 expression. Actin is shown as a loading control. The data shown in panels A and B were from separate experiments with cells from different donors.