CONCURRENT PRODUCTION OF INTERLEUKIN-2, INTERLEUKIN-10, AND GAMMA-INTERFERON IN THE REGIONAL LYMPH-NODES OF MICE WITH INFLUENZA PNEUMONIA

Cytokine production has been assessed at the single-cell level (ELISPO T assay) for freshly isolated mediastinal lymph node cells from C57BL/ 6 mice with primary, nonfatal influenza pneumonia. The mediastinal lym ph node populations were also secondarily stimulated in vitro, and cul ture supernatants were assayed by enzyme-linked immunosorbent assay. B oth approaches showed minimal evidence of protein secretion for interl eukin-4 (IL-4), n-5, and tumor necrosis factor, while IL-2, IL-10, and gamma interferon (IFN-gamma) were prominent throughout the response. The numbers of IL-2, and IFN-gamma-producing cells were maximal at 7 d ays after infection, while the total counts for cells secreting IL-10 were fairly constant from day 3 to 7. The cultures that were stimulate d with virus in vitro showed an inverse relationship between IL-10 and IFN-gamma production, with IL-10 peaking on day 3 and IFN-gamma peaki ng on day 7. Lymphocytes secreting IL-2, IL-10, and/or IFN-gamma were present in CD4(+) and CD8(+) populations separated by fluorescence act ivated cell sorting, although the CD8(+) T cells produced less cytokin e and were at a relatively lower frequency. Addition of recombinant IL -10 to the virus-stimulated cultures decreased the amount of IFN-gamma that could be detected, while incorporation of a monoclonal antibody to IL-10 had the opposite effect. A neutralization experiment also ind icated that IL-2 was the principal mediator of lymphocyte proliferatio n. These experiments thus show that the developing T-cell response in the regional lymph nodes of mice with influenza cannot be rigidly cate gorized on the basis of a TH1 or TH2 phenotype and suggest possible re gulatory mechanisms.