Induction of interleukin 4 (IL-4) expression in T helper (Th) cells is not dependent on IL-4 from non-Th cells.
Interleukin 4 (IL-4) is essential for the induction of immunoglobulin E (IgE) responses in mice. Recent in vitro studies have suggested that IL-4 derived from non T helper (Th) cells, in particular from mast cells and basophils, may be essential for triggering of IL-4 expression in Th cells and may directly contribute to IgE isotype switch induction. Here, we have generated mice carrying a functional IL-4 gene only in Th cells or non-Th cells, respectively, by reconstitution of IL-4-deficient mice (IL-4T mice) with CD4+ or CD4- spleen cells from congenic wild-type animals. In mice in which only CD4+ cells are able to express IL-4, antigen-specific IgE is produced in a T cell-dependent immune response. Thus, induction of IL-4 expression in Th cells can occur in the absence of IL-4 from non-Th cells, which suggests that at least some Th cells can express IL-4 in response to another signal which has yet to be identified. No IgE is detectable, however, in mice in which only CD4- cells can express IL-4, suggesting that Th cells are the primary, if not the only source of IL-4 for initial induction of IgE synthesis.
Schmitz
J
J
Institute for Genetics, University of Cologne, Germany.
Thiel
A
A
Kühn
R
R
Rajewsky
K
K
Müller
W
W
Assenmacher
M
M
Radbruch
A
A
D000818:Animals; D005786:Gene Expression Regulation; D007073:Immunoglobulin E / Q000096:biosynthesis; D015847:Interleukin-4 / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D013601:T-Lymphocytes / Q000378:metabolism*; D006377:T-Lymphocytes, Helper-Inducer / Q000378:metabolism*
D015847:Interleukin-4; D007073:Immunoglobulin E