ENZYME-LINKED IMMUNOSORBENT ASSAYS FOR GLIADIN AND OVALBUMIN AND THEIR APPLICATION IN NORMAL SUBJECTS

Two quick, sensitive and direct sandwich enzyme-linked immunosorbent assays (ELISAs) for the measurement of gliadin and ovalbumin in serum have been developed. The ovalbumin assay has a sensitivity of 0. 14 ng/ml (2 SD from zero). Cross-reactivities with ovomucoid and conalbumin were 58% and 0.2%, respectively. No cross-reactivity was observed with bovine serum albumin (BSA), human serum albumin (HSA), gliadin and beta-lactoglobulin. The gliadin assay did not cross-react with BSA, HSA, ovalbumin and beta-lactoglobulin and had a sensitivity of 7 pg/ml. In an acute feeding study, of 6 h duration, serum ovalbumin levels were measured in five non-food-allergic subjects who had been given raw eggs (5 g ovalbumin) after an overnight fast. Following a period of at least 1 week the same subjects were given 132 g wholemeal bread (5 g gliadin) after an overnight fast, and serum gliadin levels were measured. After the consumption of raw eggs ovalbumin levels peaked between 210 and 300 min with maximum serum concentration between 0.52 and 31.08 ng/ml. After the consumption of bread, gliadin levels reached a maximum between 180 and 300 min, reaching peak levels between 1.12 and 12.2 ng/ml. We conclude that levels of detected ovalbumin were higher than those for gliadin in this group of individuals.