Dilsulfide‐linked receptors for mitogenic lectins on piglet lymphocytes

Abstract

The interaction between leucoagglutinating phytohemagglutinin (L‐PHA), con‐canavalin A (Con A), soybean agglutinin (SBA) and lentil lectin (LcH) with disulfide‐linked cell surface receptors & lymphocytes from mesenteric lymph nodes of 3‐day piglets (PMLN) was investigated. Surface radioiodinated PMLN lymphocytes were lysed with buffer containing Nonidet‐P40. The lysates were adsorbed on lectin‐agarose derivatives (or bovine serum albumin‐agarose). Eluates from the lectin‐agar‐ose derivatives were analyzed by one‐dimensional or two‐dimensional sodium dodecyl sulfate‐polyacrylamide gel electrophoresis both under reducing and non‐reducing conditions. Among the various lectin‐binding polypeptides, L‐PHA recognizes a single 92‐kDa disulfide‐linked moiety in piglet lymphocyte lysate, comprised of polydisperse 52‐kDa subunits. In addition to this apparent homodimer, SBA, Con A and LcH bind a much less prominent 82‐kDa heterodimer comprised of 47‐kDa and 37‐kDa polypeptides; these molecules are not observed in eluates of L‐PHA. Binding of the 92‐ and 82‐kDa molecules by LcH is inhibited by methyl‐a‐D‐man‐noside. These results indicate that there are two lectin‐binding disulfide‐linked glycoproteins on lymphocytes from 3‐day piglets which bind preferentially to potent mitogens. The electrophoretic properties of these molecules, under both reducing and nonreducing conditions, as well as their lectin‐binding properties are very similar to those observed for antigen receptor molecules on lymphocytes from other species.