Production of IL-4 and expression of CD40 ligand by human CD8 T cells.
BACKGROUND
The role of CD8(+) T cells in IgE synthesis remains unclear.


OBJECTIVE
The aim of this study was to investigate IL-4 production and CD40 ligand expression by human CD8(+) T cells.


METHODS
We conducted functional and phenotypic analyses of human T cells in peritoneal washings from severe combined immunodeficiency mice reconstituted with PBMCs from normal and atopic human donors. We also examined the expression of IL-4 and CD40 ligand by CD8(+) T cells from a patient with adenosine deaminase deficiency who received autologous T cell-directed gene therapy.


RESULTS
Transfer of atopic cells into the mice caused production of IgE and IgG with increased expression of IL-4 and CD40 ligand mRNA. In addition, both intracellular IL-4 and cell surface CD40 ligand were detected in CD8(+) and in CD4(+) T cells. CD8(+) T-cell lines generated from the patient's T cells carrying the adenosine deaminase gene expressed not only IL-4 mRNA and protein but also CD40 ligand mRNA and protein after being stimulated with an anti-CD3 mAb. After anti-CD3 stimulation and paraformaldehyde fixation, CD8(+) T cells induced IgE synthesis by normal human B cells in the presence of recombinant IL-4.


CONCLUSIONS
Taken together, these results demonstrate that IL-4-producing and CD40 ligand-expressing CD8(+) cells are detectable among human T cells and suggest that such cells may promote IgE production by B cells under some conditions.
D000243:Adenosine Deaminase / Q000172:deficiency; D000818:Animals; D023201:CD40 Ligand; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D002460:Cell Line; D015316:Genetic Therapy; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000097:blood; D007073:Immunoglobulin E / Q000378:metabolism; D015847:Interleukin-4 / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D051379:Mice; D016513:Mice, SCID; D010529:Peritoneal Cavity / Q000166:cytology; D010641:Phenotype