Women in Labour

Abstract

CD4⁺ T cells produce IFN-γ contributing to corneal perforation in C57BL/6 (B6) mice after <i>Pseudomonas aeruginosa</i> infection. To determine the role of NK and NKT cells, infected corneas of B6 mice were dual immunolabeled. Initially, more NKT than NK cells were detected, but as disease progressed, NK cells increased, while NKT cells decreased. Therefore, B6 mice were depleted of NK/NKT cells with anti-asialo GM1 or anti-NK1.1 Ab. Either treatment accelerated time to perforation, increased bacterial load and polymorphonuclear neutrophils, but decreased IFN-γ and IL-12p40 mRNA expression vs controls. Next, RAG-1 knockout (−/−; no T/NKT cells), B6.TCR Jα281^−/− (NKT cell deficient), α-galactosylceramide (αGalCer) (anergized NKT cells) injected and IL-12p40^−/− vs B6 controls were tested. IFN-γ mRNA was undetectable in RAG-1^−/−- and αGalCer-treated mice at 5 h and was significantly reduced vs controls at 1 day postinfection. It also was reduced significantly in B6.TCR Jα281^−/−, αGalCer-treated, and IL-12p40^−/− (activated CD4⁺ T cells also reduced) vs control mice at 5 days postinfection. In vitro studies tested whether endotoxin (LPS) stimulated Langerhans cells and macrophages (Mφ; from B6 mice) provided signals to activate NKT cells. LPS up-regulated mRNA expression for IL-12p40, costimulatory molecules CD80 and CD86, NF-κB, and CD1d, and addition of rIFN-γ potentiated Mφ CD1d levels. Together, these data suggest that Langerhans cell/Mφ recognition of microbial LPS regulates IL-12p40 (and CD1d) driven IFN-γ production by NKT cells, that IFN-γ is required to optimally activate NK cells to produce IFN-γ, and that depletion of both NKT/NK cells results in earlier corneal perforation.