“…In addition, these ther mostable antigens are responsible for the major allergenic activity of birch pollen extracts and are more readily extracted from birch pollen than the other antigens. The allergenic thermostable antigens of birch pollen have counterparts, particular ly in the pollen of alder, but also to some extent in that of hazel and aspen, as well as in hazelnut.Conventional allergen extracts widely used in medicine for the diag nosis and treatment of atopic diseases are very complex mixtures, con taining several antigenic components [1-8, 24-27, 37-39, 42, 45], Since pollen allergy is the 'classical' atopic state, the majority of antigen ana lyses of crude allergen solutions have been performed on pollen extracts [3-8, 18-26, 30, 35,45], Extracts of ragweed and grass pollen contain 13-15 antigens, capable of inducing formation of precipitating antibodies in the rabbit [7,8]. Some of these antigens have been related to allergen activity [6-8, 20, 24-26, 41], but many of them seem to be of little significance as causal factors in human atopic disease.…”