Goats' milk of defective alpha(s1)-casein genotype decreases intestinal and systemic sensitization to beta-lactoglobulin in guinea pigs

Contradictory results have been reported on the use of goats' milk in cows milk allergy. In this study the hypothesis was tested, using a guinea pig m odel of cows' milk allergy, that these discrepancies could be due to the hi gh genetic polymorphism of goats' milk proteins. Forty guinea pigs were fed over a 20 d period with pelleted diets containing one of the following: so yabean proteins (group S). cows' milk proteins (group CM), goats' milk prot eins with high (group GM1) or low (group GM2) alpha (s1)-casein content,. P arenteral sensitization to GM1 and GM2 proteins was also assessed. The sens itization was measured (1) by systemic IgG1 antibodies directed against bov ine or caprine beta -lactoglobulin (beta -lg), alpha -lactalbumin (alpha -l a) and whole caseins. and (2) by intestinal anaphylaxis measured in vitro i n Ussing chambers. by the rise in short-circuit current (Delta Isc) in resp onse to milk proteins. Guinea pigs fed on CM and GM1 developed high titres (> 1500) of anti-beta -lg IgG1, with an important cross reactivity between goat and cow beta -lg. However, in guinea pigs fed on GM2. anti-goat beta - lg IgG1 antibodies were significantly decreased compared with GM1 guinea pi gs (mean IgG1 titres were 546 and 2046 respectively), and the intestinal an aphylaxis was significantly decreased (3.5+/-4.5 muA/cm(2)) compared with t hat observed in GM1 guinea pigs (8.3+/-7.6 muA/cm(2)). Animals receiving GM 1 or GM2 proteins via the parenteral route developed a marked sensitization . These results suggest that the discrepancies observed in the use of goats milk in cows' milk allergy could be due. at least, in part, to the high ge netic polymorphism of goats' milk proteins.