IgE Ab binding to natural and recombinant Bla g 5 was found in 27/40 (67.5%) and 29/40 (72.5%) of sera from CR-allergic patients, as measured by RIA. 5 out of 7 CR-allergic patients tested showed a positive skin reaction (>8×8-mm wheal) to rBla g 5, at conc. of 10(-4)-10(-1) μg/ml