A subset of CD8+ T cells from allergic patients produce IL-4 and stimulate IgE production in vitro.
OBJECTIVE
A subset of IL-4 producing CD8+ T cells was recently identified in HIV patients. Based on these findings we examined whether IL-4 producing CD8+ T cells would also be present in allergic patients and what would be the functional relevance of this T-cell population.


METHODS
We investigated the role of CD8+ T cells in IgE production of allergic diseases by analysing the cytokine profile of individual CD4+ and CD8+ T cells.


RESULTS
In allergic patients about twice as many CD4+ T cells and six times as many CD8+ T cells produced IL-4 as in non-allergic controls. In contrast the frequency of IFNgamma+ T-cell subsets did not significantly differ between the allergic and non-allergic individuals. The frequency of IL4+ CD8+ T cells correlated with the level of serum IgE. Coculture experiments with T cells or purified CD8+ T cells together with autologous B cells indicated that CD8+ T cells enhanced IgE in vitro, but not IgM production, even when they were physically separated from B cells. This effect could be partially blocked by addition of an IL-4 binding protein, a soluble IL-4 receptor indicating that IL-4 is involved in CD8+ T-cell mediated IgE production.


CONCLUSIONS
These data indicate a positive role of IL-4 secreting CD8+ T cells in IgE regulation in allergic patients.
Meissner
N
N
Institute of Clinical Chemistry and Biochemistry, Virchow-Klinikum of the Humboldt-University, HU-Berlin, Germany.
Kussebi
F
F
Jung
T
T
Ratti
H
H
Baumgarten
C
C
Werfel
T
T
Heusser
C
C
Renz
H
H
D000328:Adult; D015415:Biomarkers / Q000032:analysis; D015496:CD4-Positive T-Lymphocytes / Q000737:chemistry / Q000166:cytology; D018414:CD8-Positive T-Lymphocytes / Q000737:chemistry / Q000166:cytology / Q000502:physiology*; D002478:Cells, Cultured; D006801:Humans; D006967:Hypersensitivity / Q000097:blood*; D007073:Immunoglobulin E / Q000378:metabolism*; D007075:Immunoglobulin M / Q000378:metabolism; D007371:Interferon-gamma / Q000378:metabolism; D015847:Interleukin-4 / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000737:chemistry / Q000166:cytology; D016176:T-Lymphocyte Subsets / Q000737:chemistry / Q000166:cytology / Q000502:physiology*
D015415:Biomarkers; D007075:Immunoglobulin M; D015847:Interleukin-4; D007073:Immunoglobulin E; D007371:Interferon-gamma