title: A spleen-derived maturational factor allows immature thymocytes, prepared as cells bearing low amounts of surface sialic acid, to become cytotoxic T cells.
abstract: A population of immature mouse thymocytes bears low levels of surface sialic acid and can be separated from the more mature high sialic acid-bearing thymocytes by selective agglutination with the sialic acid-specific lectin, lobster agglutinin 1. These immature thymocytes do not proliferate in response to concanavalin A (Con A). They do not produce interleukin 2 (IL-2), do not provide T cell help to B cells for an in vitro antibody response, and as shown here, do not become cytotoxic T lymphocytes when polyclonally stimulated with Con A + IL-2. We describe here a spleen-derived maturational factor which stimulates these immature thymocytes, in the presence of Con A and IL-2, to become cytotoxic T lymphocytes. The maturational factor is a protein secreted by Con A-stimulated mouse or rat spleen cells; it is apparently neither interleukin 1, IL-2, interleukin 3, gamma-interferon, nor combinations of these cytokines, because these materials do not replace the maturational factor. The active material in Con A-stimulated mouse spleen cell supernatant was recovered from a G-75 column in the 33,000-48,000 m.w. range. These experiments suggest that within the lobster agglutinin 1-negative thymocyte population there are cells which can mature under the influence of a spleen-derived factor. It is possible that these cells represent the small subpopulation of immature cells destined to become immunocompetent peripheral T cells. On the other hand, the factor may be rescuing cells destined to die in the thymus.
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002469:Cell Separation; D003208:Concanavalin A / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology; D007376:Interleukin-2 / Q000494:pharmacology; D037102:Lectins; D008213:Lymphocyte Activation / Q000187:drug effects; D008222:Lymphokines / Q000302:isolation & purification / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D019158:N-Acetylneuraminic Acid; D063265:Sialic Acid Binding Immunoglobulin-like Lectins; D012794:Sialic Acids / Q000032:analysis; D013268:Stimulation, Chemical; D013601:T-Lymphocytes / Q000032:analysis / Q000145:classification* / Q000187:drug effects; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology*
chemical_list: D007376:Interleukin-2; D037102:Lectins; D008222:Lymphokines; D063265:Sialic Acid Binding Immunoglobulin-like Lectins; D012794:Sialic Acids; D003208:Concanavalin A; D007371:Interferon-gamma; D019158:N-Acetylneuraminic Acid