IDENTIFICATION OF SOYBEAN ALLERGENS AND IMMUNE-MECHANISMS OF DIETARY SENSITIVITIES IN PRERUMINANT CALVES

The allergenicity of soya proteins was assessed by direct skin testing and by in vitro lymphoproliferation tests in calves fed milk substitu tes containing skim milk powder (SMP) or an antigenic heated soya flou r (HSF). During the last three weeks of treatment, the calves were inj ected intradermally with raw soya flour (RSF), HSF, hydrolysed soya pr otein isolate (HSPI), SMP or purified soya proteins, after being preme dicated with anti-histamine or not. Peripheral blood leucocytes (PBL) were grown over five days with various mitogens or dietary antigens, a nd the incorporation of tritiated thymidine was measured. Strong skin oedema reactions to RSF, HSF and all the purified proteins were observ ed in the calves fed HSF at various times up to 24 hours after injecti on. The skin oedema was largely prevented by premedication with anti-h istamine. A strong delayed skin thickening was observed in the calves fed HSF for up to five days with beta-conglycinin. PBL from the calves fed HSF proliferated in vitro with HSF, HSPI and beta-conglycinin, bu t not with glycinin. Thus, most proteins from soyabean were implicated in the immediate and semi-delayed immune reactions, whereas beta-cong lycinin was strongly involved in a delayed type hypersensitivity in ca lves.