Interleukin 2 enhancement of lymphokine secretion by T lymphocytes: analysis of established clones and primary limiting dilution microcultures.
The effect of exogenous interleukin 2 (IL 2) on lymphokine production by T lymphocytes was examined in two systems: the secretion of macrophage-activating factor (MAF) and interferon (IFN) by cloned long-term T cell lines, and a limiting dilution system for estimating the frequency of precursors of MAF-secreting cells in normal spleen. An IL 2-containing, MAF- and IFN-free supernatant from the EL-4 thymoma (EL-4 SN) significantly enhanced release of MAF and IFN by mitogen- or antigen-stimulated, cytolytic or noncytolytic T lymphocyte clones directed against alloantigens or Moloney leukemia virus-associated antigens. Highly purified IL 2 produced equivalent enhancement as EL-4 SN in cultures of alloreactive clones stimulated with concanavalin A. Kinetics experiments showed that EL-4 SN increased both the rate and duration of MAF release by T cell clones. EL-4 SN also increased MAF production when added during restimulation of limiting dilution cultures of positively selected Lyt-2+ and Lyt-2- C57BL/6 splenic T lymphocytes activated against DBA/2 alloantigens. This enhancement resulted in a threefold increase in the apparent precursor frequency of MAF-secreting cells among Lyt-2+ lymphocytes, but did not affect the frequency among Lyt-2- cells. Additional analysis indicated that average MAF production in cultures of Lyt-2-+ cells was sixfold lower than in cultures of Lyt-2- cells, and hence that EL-4 SN allowed detection of a significant proportion of Lyt-2+ cell cultures secreting low levels of MAF. Under these improved conditions, the MAF assay detected the majority of responding Lyt-2+ and Lyt-2- lymphocytes.
D000818:Animals; D000950:Antigens, Ly / Q000276:immunology; D002460:Cell Line; D002999:Clone Cells / Q000276:immunology / Q000378:metabolism; D007376:Interleukin-2 / Q000502:physiology*; D007959:Lymphocyte Culture Test, Mixed; D008222:Lymphokines / Q000096:biosynthesis / Q000378:metabolism*; D016215:Macrophage-Activating Factors; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D013234:Stem Cells / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism*
D000950:Antigens, Ly; D007376:Interleukin-2; D008222:Lymphokines; D016215:Macrophage-Activating Factors