ALLERGENICITY AND LYMPHOCYTE-STIMULATING PROPERTY OF RICE PROTEIN

Two protein fractions of rice grain, glutelin and globulin, were prepared by dilute alkali and salt extraction, respectively. The globulin fraction was separated into GI-1, GI-2, and GI-3 fractions by Sephadex G-200 column chromatography. The allergenic activities and lymphocyte-stimulating properties of these fractions were investigated by the radioallergosorbent test (RAST) with sera from 6 individuals who showed immediate skin reaction to soluble rice extract and by 3H-thymidine incorporation tests with 5 subjects with indurated skin reaction of delayed onset. All fractions were found to be reactive with specific IgE antibody, and GI-1 and G-2 revealed lymphocyte-stimulating activity. RAST inhibition revealed considerable cross-reactivity of IgE antibody with the glutelin and globulin fractions. When the glutelin and globulin fractions were heated at 60 °C for 1 hr, 100 °C for 2 min, or 100 °C for 10 min, RAST activities were reduced to 40%-70% of native. On the other hand, lymphocyte-stimulating activities of the globulin fraction heated at 60 °C for 1 hr or 100 °C for 2 min were enhanced up to 6 times of native activities, while those of identically treated glutelin fractions remained unchanged. © 1979.