Red cell Th activation: biochemical studies

Summary. The peanut agglutinin from Arachis hypogea is a lectin that reacts with red blood cells expressing the Th antigen. The Th antigen has been said to be qualitatively similar to the T antigen, a well‐defined antigen due to desialylation of glycophorin A and B that also reacts with the peanut agglutinin. We examined Th activated red blood cells from two patients with Fanconi's anaemia using ¹²⁵I radio‐labelled peanut agglutinin as a probe in Western blotting of red blood cell membrane proteins. We also probed the surface of intact Th activated red blood cells for structures related to the T antigen using [³H]sialic acid and a purified sialyltransferase. Neither of these techniques found antigens on the Th activated red blood cells that were similar to the antigen found on T activated red blood cells. These results show that the Th antigen in Fanconi's anaemia is qualitatively different to the antigen found in T activation.