Identification of interleukin 2‐producing T helper cells within murine Lyt‐2+T lymphocytes: frequency, specificity and clonal segregation from Lyt‐2+precursors of cytotoxic T lymphocytes

摘要

AbstractThe prime aim of this study was to assess whether the autonomous primary mixed lymphocyte culture response of Lyt‐2+T cells towards class I major histocompatibility complex (MHC) antigens reflects in terms of interleukin 2 (IL2) production and cytotoxicity the activation of multifunctional Lyt‐2+T cells, or the activation of functionally distinct T cell subsets. The results demonstrate that highly purified Lyt‐2+T cells proliferate in response to class I MHC antigens, as opposed to L3T4+T cells which react towards class II MHC antigens. In both responder cell types proliferative responses are associated with IL2 secretion, while only Lyt‐2+T cells develop measurable cytotoxic effector cells. The precursor frequency of IL 2‐producing helper cells in MHC class I‐reactive Lyt‐2+T cells equals that in MHC class II‐reactive L3T4+T cells (f = 1/500–1/1000). In clonal segregation analysis>90% of Lyt‐2+colonies secreting IL2 do not develop cytotoxic activity, while>90% of Lyt‐2+cytotoxic T cells fail to produce detectable IL2. A minority of<10% of Lyt‐2+T cells appears to be bifunctional. As such the results point out the existence of functionally committed T cells within class I MHC‐reactive Lyt‐2+T cells able to produce either IL2 or to develop in