A comparison of the antigenicity of soya-bean-based infant formulas

Abstract

1. The antigenicity of four soya-bean-based infant formulas (Prosobee powder, Prosobee liquid concentrate (Mead Johnson, Uxbridge, Middx), Wysoy (Wyeth, Maidenhead, Berks) and Formula S (Cow and Gate, Trowbridge, Wilts)) was measured by enzyme-linked immunosorbent assays (ELISAs) specific for glycinin and P-conglycinin. Results were compared with in vivo assessments of antigenicity using guinea-pigs, rabbits and calves.2. The levels of antigenic glycinin and ,&onglycinin in Wysoy and Formula S were below the limits of detection of the ELISA. Both these proteins were detected in Prosobee powder and Prosobee liquid concentrate with the highest levels, especially for glycinin, being present in Prosobee powder.3. Wysoy was sufficiently antigenic to evoke a soya-bean-specific serum antibody response in rabbits injected with this formula emulsified in complete Freunds adjuvant. A significantly greater response was obtained when rabbits were similarly injected with Prosobee powder.4. The formulas varied in their ability to sensitize guinea-pigs for both anaphylaxis and antibody production when given orally, although the differences were not statistically significant. Prosobee powder appeared to be the most antigenic and Formula S the least, with Prosobee liquid concentrate and Wysoy being intermediate.5. Similar variations in antigenicity were observed when Prosobee powder, Wysoy and Formula S were fed to soya-bean-sensitive calves. These formulas were all capable of provoking intestinal disturbances (seen as increased ileal flow-rate, decreased small intestinal transit time and decreased nitrogen absorption) but the most severe reactions were seen when Prosobee powder was fed and the least with Formula S.6. Thus the four soya-bean-based infant formulas showed considerable differences in antigenicity. In vivo studies using guinea-pigs, rabbits and calves were in good agreement and broadly correlated with the immunochemical assessment of antigenicity. However, the in vitro and in vivo results did not correspond exactly and levels of glycinin and ,L?-conglycinin below the limit of detection by ELISA could evoke an immune response in the different animal species. We believe that these variations in antigenicity of different commercial products prepared from isolated soya-bean protein may be important when interpreting the results from studies of the development of allergy in infants given soya-bean-based formulas.

Digestion of soybean globulins, glycinin, α-conglycinin and β-conglycinin in the preruminant and the ruminant calf

“…Also, acidic subunits of both globulins appeared to be more susceptible to enzyme attack than basic subunits (Lynch et al 1988;Newbold and Rust 1990;Romagnolo et al 1990), as has been observed with pea globulins (Spencer et al 1988). Differences also exist among strains of rumen bacteria in their ability to degrade soybean globulins (Lynch et al 1988 (Lallbs et al 7992) and in dairy cows consuming grass (Stokes 1984 (Heppell et al 1987), the passive haemagglutination inhibition test (Barratt et aL. 1978 Sissons et al 1982; Sissons and Thurston 1984) and the radial immunodiffusion assay (Srihara et al 1982;Mir et al 1989).…”

“…Immunometric ELISA's were set up for each purified soy globulin utilizing modifications of procedures described by Heppell (1985) and Heppell et al (1987 Values were expressed as native globulin equivalents. Prior to routinely assaying residual soybean globulins in digesta, matrix effects were evaluated using ELISA.…”

The postnatal development of the mucosal immune system and mucosal tolerance in domestic animals

“…A frequently-observed features in domestic species (and in human infants) which differs from the protocols in laboratory rodents is the appearance of systemic, IgG antibody to fed proteins after the initial feed. The problem of feeding large amounts of unprocessed soya to calves has been well documented and associated with the persistent expression of active, IgG antibody responses to soya proteins [28]. Similarly, piglets weaned onto soya-or eggbased diets developed levels of antibody comparable to those produced after primary systemic injection [7] while 7-9 month old cats fed soya or casein diets also developed serum antibody [14].…”

Soyabean antigen survival along the digestive tract of the dairy calf at weaning

“…Digesta were collected through weaning (Lall6s and Poncet, 1990). Immunoreactive glycinin (glyc) and [3-conglycinin (pcong) were assayed in feeds and digesta by ELISA (Heppell et al, 1987) using antibodies against native proteins.…”