Anti-major histocompatibility complex (anti-MHC)
antibodies (Abs) and antipolymorphonuclear neutrophil (anti-PMN) Abs are generally considered as the main causes of the development of
transfusion-related acute lung injury (
TRALI), which is one of the most severe and sometimes lethal side effects of transfusion. These Abs are postulated to activate recipient's leucocytes, resulting in the release of soluble factors such as
reactive oxygen species and detrimental
cytokines and
chemokines. The harmful effects on the lung tissues and resident leucocytes of these malignant factors are suspected to be profoundly involved in
TRALI reactions. Several reports have indicated the principle effect of biologically active
lipids on the pathogenesis of
TRALI. However, the precise mechanisms of
TRALI development remain unclear. To resolve this issue, we have been investigating
cytokines that induce continuous
inflammation of the lungs, specifically focusing on the
cytokines derived from activated PMNs. We observed that the
granulocyte-macrophage colony-stimulating factor (
GM-CSF) markedly enhances the expression of MHC class II DR in PMNs. Moreover, MHC class II DR-expressing PMNs were also proved to express a high-affinity receptor for
immunoglobulin E (
IgE) (FcepsilonRI) and to produce tumour
necrosis factor-
alpha, interferon-gamma and
interleukin-18 following a challenge with an anti-MHC class II DR monoclonal Ab (MoAb) or anti-DR antiserum. It is strongly suggested that amongst various inflammatory mediators, at least these three
cytokines may contribute to the duration of inflammatory reactions in the lungs. Furthermore, FcepsilonRI expression, in
GM-CSF-treated PMNs, suggests the involvement of PMNs in
IgE-mediated immune reactions.