Soybean hydrophobic protein and soybean hull allergy

Report on an investigation of asthma and respiratory symptoms among workers at a soy processing plant.

“…These two antigens were in the higher-molecularweight range, suggesting that soy allergy among Solae participants is distinct from that of allergy to low-molecular-weight hull antigens observed in community epidemics of asthma in Spain [Gonzalez et al 1994;Codina et al 1997]. This finding is consistent with the fact that soy beans are de-hulled before processing at Solae, which would be expected to result in very limited, if any, exposure to hull antigens at the plant.…”

“…Furthermore, asthmatic patients presenting on epidemic days were far more likely to have IgE antibodies to soybean dust than asthma patients presenting on non-epidemic days . Several low-molecular-weight proteins (7-8 kDa) concentrated in the soybean hull were implicated [Gonzalez et al 1994;Codina et al 1997]. Ultimately, the epidemics were halted after soybean silos in the harbor were fitted with filters, providing further evidence of a causal relationship [Picado 1992].…”

Immunoquantitative Measurement of Soybean Aeroallergen Emissions

“…Rodrigo et al (8) demonstrated that during an epidemic the serum of patients with asthma reacted specifically to an acidic, low-molecular mass (LMM) protein (<14 kDa) located principally in hulls and dust of soybeans unloaded in the harbour. Two proteins located in soybean hulls were later shown to be the main allergens responsible for this asthma epidemic (9). Both proteins are isoallergens (Gly m 1a and Gly m 1b) with molecular weights of 7.0 and 7.5 kDa, respectively, and are highly homologous with the hydrophobic soybean protein (HSP) described by Odani et al (10).…”

“…It has been established that the allergens responsible for occupational asthma in bakers exposed to soy flour are not the same as those involved in soy dust-induced asthma epidemics, and the proteins causing both these conditions may differ from those involved in cases of adverse reactions following oral ingestion of soy (19). The low-molecular weight (LMW) soybean hull proteins (8,20), Gly m 1 (9,21) and Gly m 2 (22) have been identified as the main allergens that cause the asthma outbreaks, while allergens responsible for soybean flour-induced occupational asthma would be mainly high-molecular weight (HMW) p r o t e i n s ( 1 7 , 1 9 ) . S o y h u l l c o m p o n e n t s m a y , h o w e v e r , a l s o h a v e b e e n i n v o l v e d i n occupational asthma reported in animal feed manufacturers (23).…”

“…Thus, the data strongly suggest that airborne samples from different work environments with 'soy exposure' may contain 'soy dust' with quite different composition. For example, soy hull antigens are more commonly found at sites where whole soybeans are unloaded and stored, such as at the harbour silos in Barcelona (8,9), whereas in a work environment where processed soybean and flours are used, such as feed and food industries, the airborne soy proteins maybe mainly soy flour-derived. Differences in soy allergen composition of airborne samples and differences in ELISA antibody specificity might also explain the very low correlations between some of the assays.…”