Peripheral blood mononuclear cells from 16 children with atopic disease (range of IgE levels: 33 - 2892 kU/l) and 12 age matched controls were stimulated either with mAbs specific for CD3, CD2, CD3 plus CD28, CD2 plus CD28, with Tetanus Toroid, SEA, or PHA plus PMA and their cell proliferation was determined. In addition, their cytokine production (IL2, IL4, IL10, IFN gamma) following selected stimuli was measured. We found that the cells from atopics proliferated significantly better in response to CD2 stimulation than control cells, with no difference in response to CD3 or SEA stimulation. Furthermore, cells from atopics produced significantly higher amounts of IL4 than cells from controls, a difference most pronounced following CD2 plus CD28 stimulation. No differential production was found for IL10 and IFN gamma. We conclude that in atopic children with moderately elevated IgE a hyperreactivity of the CD2 pathway of stimulation and a clear elevation of IL4 but not of IL10 or IFN gamma production can be demonstrated.