Differential activation of cytokine genes in normal CD4-bearing T cells is stimulus dependent.
Studies of cloned CD4+ T cell lines have shown that they can be separated into two distinct subsets with distinctions in their functional capabilities and by the differential release of either interleukin 2 (IL 2) (TH1/inflammatory type) or IL 4 (TH2/helper type) upon activation. To establish if in vivo-derived CD4+ T cells can exhibit distinct subsets we have investigated whether normal CD4+ T cells demonstrate differential expression of IL 2 and IL 4 mRNA, and secretion of IL 2 and IL 4 after primary stimulation in vitro. Utilizing the technique of in situ hybridization IL 2 and IL 4 gene expression in individual CD4+ T cells was readily detectable after concanavalin A (Con A) phytohemagglutinin (PHA) or pokeweed mitogen (PWM)-mediated activation. The frequencies of activated T cells producing IL 2 and IL 4 mRNA after Con A or PHA activation were approximately equivalent (30-40% of cells); however, after PWM activation the number of CD4+ T cells expressing IL 4 mRNA (78%) was more than twofold greater than the number of cells producing IL 2 mRNA (30%). Maximal levels of IL 2 gene expression occurred 24 h after mitogen activation whereas the highest levels of IL 4 mRNA were not detected until 48 h after mitogen activation. Similar distinctions in the kinetics of IL 2 and IL 4 secretion after mitogen activation were also found demonstrating good concordance in the observed expression of IL 2 and IL 4 mRNA and the levels of secreted lymphokines detected by bioassay. Most importantly, we have shown by in situ hybridization analysis that the majority of individual CD4+ T cells produce only IL 2 or IL 4 mRNA, and not both, after primary activation in vitro. By contrast, most CD4+ T cells activated in the presence of PMA and ionophore express both IL 2 and IL 4 mRNA. Our studies demonstrate that in normal, non-clonal populations of CD4+ T cells, the production of IL 2 and IL 4 is independently regulated in the majority of cells and appears to be stimulus dependent.
Carding
S R
SR
Section of Immunology, Howard Hughes Medical Institute, New Haven, CT 06510.
West
J
J
Woods
A
A
Bottomly
K
K
D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte; D002999:Clone Cells / Q000145:classification / Q000276:immunology / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D007376:Interleukin-2 / Q000096:biosynthesis; D015847:Interleukin-4; D007378:Interleukins / Q000096:biosynthesis; D007476:Ionophores / Q000494:pharmacology; D007700:Kinetics; D008213:Lymphocyte Activation / Q000187:drug effects; D008222:Lymphokines / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D010641:Phenotype; D012333:RNA, Messenger / Q000096:biosynthesis; D011971:Receptors, Immunologic / Q000032:analysis; D013601:T-Lymphocytes / Q000145:classification* / Q000276:immunology / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000945:Antigens, Differentiation, T-Lymphocyte; D007376:Interleukin-2; D007378:Interleukins; D007476:Ionophores; D008222:Lymphokines; D012333:RNA, Messenger; D011971:Receptors, Immunologic; D015847:Interleukin-4; D013755:Tetradecanoylphorbol Acetate