TH1 pattern of cytokine secretion by splenic cells from pyelonephritic mice after in-vitro stimulation with hsp-65 of Escherichia coli

Abstract

Splenic lymphocytes and peritoneal macrophages from BALB/c mice with Escherichia coli pyelonephritis were obtained at various intervals after infection. These cells were stimulated in vitro with different antigens and cytokine release was assayed in the supernate of the cultured cells. It was observed that both specific antigens such as outer-membrane proteins (OMPs), porins and heat-shock protein-65 (hsp-65), as well as non-specific mitogens such as phytohaemagglutinin (PHA), were able to induce cytokine production by splenic cells from infected mice. Of all these antigens, hsp-65 was found to be the best inducer of cytokine release. In the acute stage of pyelonephritis, the release of interleukin-2 (IL-2) and interferon-γ (IFN-γ) was found to increase with time; both reached their peak values on the seventh day after infection. The TH1 pattern of cytokine secretion by splenic cells was observed, i.e., IL-2 and IFN-γ, whereas there was complete absence of IL-4 secretion. In the chronic stage of pyelonephritis, i.e., 150 days after infection, a decrease in the level of IL-2 and IFN-γ was observed. Peritoneal macrophages released IL-1 on stimulation with hsp-65, which increased with the progression of disease. The possible implications of this study for the disease process are discussed.