Clonal heterogeneity in colony stimulating factor production by murine T lymphocytes

A panel of 55 alloreactive murine T‐lymphocyte clones was screened for the production of granulocyte‐macrophage colony stimulating factor (GM‐CSF), multilineage CSF (multi‐CSF), human‐active eosinophil CSF (human‐active EOCSF), and interleukin 2 (IL‐2) in response to stimulation with the lectin concanavalin A. Many clones were also characterized for cytolytic specificity and expression of the T‐cell antigen receptor‐associated surface markers Lyt‐2 and L3T4, which reflect their specificity for Class I (H‐2K, H‐2D) or Class II (H‐2I, MIs) histocompatibility antigens, respectively. Eighty percent of the clones secreted detectable quantities of at least one of the four factors measured. Of the factor‐producing clones, all appeared to secrete GM‐CSF and half also secreted multi‐CSF. A subpopulation of multi‐CSF producers also released human‐active EO‐CSF. More than half of the factor‐producing clones secreted detectable IL‐2; whereas the IL‐2 producing clones included some that did not secrete multi‐CSF, IL‐2 production was always associated with concomitant synthesis of GM‐CSF. Comparison of the range and quantities of factors secreted by Lyt‐2 + and L3T4 + clones indicated that more L3T4 + clones produced measurable titers of the four factors; on average, this group also secreted 10‐ to 100‐fold higher titers of both the hemopoietic regulators and IL‐2 than Lyt‐2 + clones. Cells of the L3T4 + phenotype would therefore be expected to account for the majority of CSF and IL‐2 secretion by polyclonal populations of activated T lymphocytes.