The Interaction of Nonmitogenic and Mitogenic Lectins with T Lymphocytes: Association of Cellular Receptor Sites

The relationship between the surface receptors on neuraminidase-treated human blood lymphocytes for the mitogenic lectins Phaseolus vulgaris leukoagglutinin (La), concanavalin A (Con A) and soy bean agglutinin (SBA) and the non-mitogenic lectin Helix pomatia A hemagglutinin (HP) was investigated. Two different techniques, co-capping with different fluorochrome-labeled lectins and cell binding-inhibition experiments with 125I-labeled lectins, were used. The results demonstrated that the nonmitogenic lectin HP and the mitogenic lectins SBA, La and Con A bind either to the same macromolecule (s) or to different but physically linked macromolecules on the surface of human T lymphocytes. In contrast, only part of beta2-microglobulin (beta2-m) or beta2-m-bearing complexes, appear to be physically linked to the lectin receptor complex(es). On the lectin-binding substance(s) at least two saccharide structures were recognized, one of which binds both HP and SBA and another which binds SBA and La (and probably also Con A) but not HP.