Lymphocyte proliferation in mice immunized with rGroEL in the presence of IL-22. Groups of mice (n=6 each) were immunized with rGroEL/rGroEL+rIL-22 on days 0, 7 and 28. Control animals were injected with PBS. Seven days after the last immunization, splenocytes were isolated from mice and cultured (1×106 cells/well) in the absence (unstimulated) or presence (stimulated) of rGroEL for 72 h in a CO2 incubator at 37 °C. Lymphocyte proliferation was determined by MTT assay and absorbance was measured at 570 nm. The data were compared by one-way analysis of variance between different immunized groups. *P<0.01 vs. control, #P<0.01 vs. rGroEL. MTT, 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazoliumbromide; PBS, phosphate-buffered saline.