Isoforms of Group 1 Allergens from a Tropical/Subtropical Para Grass (Urochloa mutica) Display Different Levels of IgE Reactivity and Cross-reactivity

Summary: Group 1 grass pollen allergens, or beta-expansins, are the most important major allergens from tropical/subtropical grasses. This study aimed to investigate the sequence similarity, and immunoreactivity of group 1 allergens from Para grass (Urochloa mutica). Three isoforms (Uro m 1.01, Uro m 1.02, and Uro m 1.03) were cloned from cDNA of Para grass pollen. The acidic-neutral isoforms rUro m 1.01 and rUro m 1.02 could effectively inhibited beta-expansins in pollen extract of Bermuda and Johnson grasses, suggesting that these isoforms could be major cross-reacting allergens among these grasses. In contrast, the basic isoform rUro m 1.03 had limited IgE reactivity. Thus, group 1 allergens both acidic-neutral and basic isoforms could have markedly different IgE reactivity.