Role of CD7 expressed in lung microvascular endothelial cells as Fc receptor for immunoglobulin M.

Immunoglobulins (Igs) against anti-human white blood cells are putative contributors to the development of transfusion-related adverse effects, particularly transfusion-related acute lung injury (TRALI). Studies of Igs that are considered to be implicated in transfusion-related adverse effects have mainly focused on immunoglobulin G (IgG) class antibodies (Abs). In the authors' previous in vitro study, the association of polymorphonuclear neutrophils (PMNs) and lung microvascular endothelial (LME) cells was up-regulated in the presence of normal human serum-derived IgMs, when F(ab')2 fragments of IgMs were specific to low-affinity Fc receptors (FcR) for IgG, namely, Fcgamma R III (CD16) and Fcgamma RII (CD32). In this study, the authors found that CD7 antigen notably expresses in LME cells and that it acts as an Fc receptor for IgM in LME cells.