IL-4 acts synergistically on the IL-2 response of an autoreactive T-cell clone; synergism correlates with increased intracellular IL-2, but not with a modified IL-2 receptor expression.
TE44, an H-2b-restricted, self-reactive T-cell line, did not produce autocrine-acting growth factors, neither after antigenic nor after mitogenic activation; they remained for their proliferation completely dependent on exogenously added IL-2. Administration of IL-4, which poorly promotes growth by itself, resulted in a 5- to 10-fold enhancement of the specific biological activity of IL-2 on antigen-activated TE44-cells. This synergism was exerted nonreciprocally and required the presence of both lymphokines. IL-4 did not affect the number, nor the affinity, nor the rate of internalization of the high-affinity receptors for IL-2. However, increased levels of intracellular IL-2 were observed, suggesting an effect of IL-4 on the turnover of IL-2. This might allow a prolonged activity of IL-2 or IL-2-associated molecules inside the cell. Furthermore, the lack of autocrine growth factor production by antigen-stimulated TE44 is discussed in terms of its relationship to the autoimmune specificity of these T-cells.
Laboratory of Molecular Biology, State University of Ghent, Belgium.
P
P
Vandenabeele
J
J
Grooten
W
W
Fiers
D000818:Animals; D001324:Autoantigens / Q000276:immunology; D015551:Autoimmunity; D002460:Cell Line; D004357:Drug Synergism; D004705:Endocytosis / Q000187:drug effects; D006133:Growth Substances / Q000096:biosynthesis; D007376:Interleukin-2 / Q000008:administration & dosage* / Q000378:metabolism; D015847:Interleukin-4 / Q000008:administration & dosage*; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D015375:Receptors, Interleukin-2 / Q000378:metabolism; D013601:T-Lymphocytes / Q000502:physiology*
D001324:Autoantigens; D006133:Growth Substances; D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D015847:Interleukin-4