Concurrent production of interleukin-2, interleukin-10, and gamma interferon in the regional lymph nodes of mice with influenza pneumonia

Abstract

Cytokine production has been assessed at the single-cell level (ELISPOT assay) for freshly isolated mediastinal lymph node cells from C57BL/6 mice with primary, nonfatal influenza pneumonia. The mediastinal lymph node populations were also secondarily stimulated in vitro, and culture supernatants were assayed by enzyme-linked immunosorbent assay. Both approaches showed minimal evidence of protein secretion for interleukin-4 (IL-4), IL-5, and tumor necrosis factor, while IL-2, IL-10, and gamma interferon (IFN-y) were prominent throughout the response. The numbers of IL-2and IFN-y-producing cells were maximal at 7 days after infection, while the total counts for cells secreting IL-10 were fairly constant from day 3 to 7. The cultures that were stimulated with virus in vitro showed an inverse relationship between IL-10 and IFN-y production, with IL-10 peaking on day 3 and IFN-7y peaking on day 7. Lymphocytes secreting IL-2, IL-10, and/or IFN-'y were present in CD4+ and CD8+ populations separated by fluorescence-activated cell sorting, although the CD8+ T cells produced less cytokine and were at a relatively lower frequency. Addition of recombinant IL-10 to the virus-stimulated cultures decreased the amount of IFN-y that could be detected, while incorporation of a monoclonal antibody to IL-10 had the opposite effect. A neutralization experiment also indicated that IL-2 was the principal mediator of lymphocyte proliferation. These experiments thus show that the developing T-cell response in the regional lymph nodes of mice with influenza cannot be rigidly categorized on the basis of a TH1 or TH2 phenotype and suggest possible regulatory mechanisms. Recent experiments with several RNA viruses show clearly that the process of clonal expansion and differentiation leading to the development of a primary CD8+ T-cell response occurs in regional lymphoid tissue (2, 19, 27). The CD8+ cytotoxic T-lymphocyte precursors (CTLp) then leave the lymph nodes and travel to the virus-infected target organ, where they differentiate further to become potent CTL effectors (2, 20). Other lymphocytes, probably progeny of the same clones, apparently go on to constitute the pool of memory CTLp that contributes to the maintenance of long-term protective immunity. Similar processes occur in the CD4+ T-cell and Blymphocyte populations (1, 9, 30), although less effort has been made to quantify these responses. The humoral response is clearly skewed towards production of immunoglobulin G2a (IgG2a) and IgA (3).

Metabolic host response and therapeutic approaches to influenza infection

“…Their results revealed the involvement of oxidative and nitrative stress in the pathogenesis of H1N1 influenza virus-induced acute respiratory distress syndrome (ARDS) [15]. Influenza-induced cytokines such as IFNγ stimulate NO release from human airway epithelial cells [150][151][152]. As mentioned previously, the influenza infection induces upregulation of HIF-1α.…”

The generation of memory antigen‐specific cytotoxic T cell responses by CD28/CD80 interactions in the absence of antigen

“…There is evidence that memory Tc cells immune to one particular virus can be activated in response to unrelated viral infections ( Table 1 and [28][29][30]511). A measure of bystander activation of memory Tc cells may be induced by the cytokine milieu of an inflamed local environment [52], as memory T cells are preferentially recruited to these sites [53]. Alternatively, memory T cells of high affinity may be activated by low-affinity or crossreactive antigen as suggested by the unexpectedly high levels of Tc cell cross-reactivity at the clonal level [30]; this activation may contribute to the waning of the Tc cell memory pool to earlier encountered viruses [54].…”

A question of self‐preservation: immunopathology in influenza virus infection

“…It is well known that CD4 + T helper (h) cells secrete cytokines that are involved in regulating the immune response and can be classified as either Th1 or Th2, depending on their cytokine profile. 88 Following infection with influenza A viruses, CD4 + T cells secrete a number of cytokines, including IL-2, IL-10 and IFN-g. 89,90 The possible roles of cytokines on immunopathology has been discussed at length previously, so this section will focus specifically on CD4 + T-cell function. Although IFN-g is one of the major cytokines produced by CD4 + T cells following influenza infection, the role of this cytokine in mediating immunopathology is unclear (see Cytokines and chemokines in influenza infection).…”