Low sialic acid-bearing mouse thymocytes do not express helper T cell properties in vitro.
Immature, presumably cortical, mouse thymocytes were isolated by removing mature thymocytes by agglutination with the sialic acid-specific lectin, lobster agglutinin 1 (LAg1). These immature cells do not respond to the mitogenic effects of concanavalin A (Con A), even in the presence of interleukin 2. Moreover, they do not exhibit two properties of helper T cells; they do not secrete interleukin 2 when stimulated with Con A, nor do they provide T help for an in vitro immune response by spleen B cells to the T-dependent antigen, sheep erythrocytes. LAg1-negative thymocytes fail to provide T help even though Con A is added to the cultures, regardless of the number of LAg1-negative thymocytes added per culture, and even in the presence of exogenous macrophages. Unseparated thymocytes, LAg1-positive thymocytes and cortisone-resistant thymocytes all provide T cell help under these conditions. These experiments indicate that immature, presumably cortical mouse thymocytes, isolated by virtue of their low levels of surface sialic acid, are inherently unable to provide T cell help in vitro.
D000818:Animals; D005260:Female; D006462:Hemolytic Plaque Technique; D007376:Interleukin-2 / Q000032:analysis; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D012794:Sialic Acids / Q000032:analysis*; D013601:T-Lymphocytes / Q000032:analysis* / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D013950:Thymus Gland / Q000032:analysis
D007376:Interleukin-2; D012794:Sialic Acids