Purification of a factor which provides a costimulatory signal for gamma interferon production

Abstract

A protein factor which induces high levels of gamma interferon (IFN-y) in resting splenic nonadherent cells was isolated from the sera of mice with generalized inflammation caused by endotoxic shock. The factor was highly purified by ammonium sulfate precipitation followed by ion-exchange column chromatography on DEAE-Sepharose, molecular sieving on Ultrogel AcA 44, and hydrophobic column chromatography with phenyl-Sepharose. It was further purified to apparent homogeneity by polyacrylamide gel electrophoresis. It induced IFN-y production in a dose-dependent manner in the presence of interleukin-2, monoclonal anti-CD3 antibody (anti-CD3 MAb), or concanavalin A (ConA) in spleen cells deprived of plastic plate-and nylon wool-adherent cells. Anti-CD3 MAb induced the highest level of production of the three. The factor, interleukin-2, anti-CD3 MAb, or ConA alone induced a trace of or no detectable IFN-y in these cells. The factor also exhibited an accessory function during proliferation in these cells in the presence of a suboptimal dose of ConA. However, the factor failed to stimulate IFN-y production when staphylococcal enterotoxin A, a superantigenic T-cell mitogen, was employed. Treatment with pronase or heat abolished these activities. These studies confirm the existence of a soluble protein factor which is able to exhibit a novel accessory function in IFN-y production in resting T or natural killer cells. It will be of interest to compare this factor with the recently cloned human natural killer stimulatory factor (NKSF/IL-12).

Overview of interleukin-18: more than an interferon-γ inducing factor

“…This serum activity functioned not as a direct inducer of IFN-␥ but rather as a co-stimulant together with IL-2 or mitogens. An attempt to purify the activity from post-endotoxin mouse serum revealed an apparently homogeneous 50-to 55-kDa protein [21]. Because other cytokines can act as co-stimulants for IFN-␥ production, the failure of neutralizing antibodies to IL-1, IL-4, IL-5, IL-6, or TNF to neutralize the serum activity suggested that it was a distinct factor.…”

Serum IL‐18 levels in tuberculosis: Comparison with pneumonia, lung cancer and healthy controls

“…2,3 IL-18 is a cytokine that has been identified as an interferong -inducing factor in mice infected with Propionobacterium acnes and lipopolysaccharide. 4 It plays an important role in the Th1 response. 5,6 The immune defence against Mycobacterium tuberculosis is mediated primarily by T cells, and interferon-g (IFNg ) is essential for protective immunity.…”

Interleukin-18/interferon-γ-inducing factor, a novel cytokine, up-regulates ICAM-1 (CD54) expression in KG-1 cells

“…It has recently been reported that mice injected with heat-killed Propionibacterium acnes released significantly higher levels of interferon-␥ (IFN-␥) into the circulation on challenge with T cell mitogens than mice challenged with T cell mitogens alone [1][2][3][4]. This IFN-␥ production was also induced in vivo when using lipopolysaccharide (LPS) as a mitogen instead of T cell mitogens [5][6][7]. Because it was unlikely that LPS stimulated the T cells directly, some intermediate molecules were considered to be involved.…”