Functional and phenotypic analysis of human T-cell clones which stimulate IgE production in vitro.

Peripheral blood mononuclear cells (PBMC) from a patient suffering from the hyper IgE syndrome were used to generate phytohaemagglutinin (PHA)-expanded T-cell clones (all CD4+, CD8-, CD23-). A selection of the clones was tested for their ability to help IgE secretion by culturing with normal B cells in the presence of solid-phase antibody to CD3. Supernatants were harvested on Day 7 and assayed by ELISA for IgE, IgG and IgM. Lymphokine secretion by the clones was assessed by culturing clones for 24 hr with solid-phase antibody to CD3 followed by assay of the supernatants for IL-2, IL-4 and interferon-gamma (IFN-gamma) production. In addition, clones were analysed by flow cytometry for CDw29 and CD45R expression. Initial experiments with seven clones indicated that those clones that could help IgE secretion also stimulated optimal IgG and IgM responses. All clones appeared to secrete IL-2, IL-4 and IFN-gamma, although the amounts of each varied. These results confirm recent findings that human T-cell clones do not fall into Tinf (Th1) and Th (Th2) type subsets as described in the mouse. There was no clear correlation between the lymphokines secreted by the clones and their capacity to help IgE production. However, the helper function of the clones for all isotypes, including IgE, appeared to be related to the level of expression of the surface antigen CDw29.