Increased concentration of soluble leukocyte-associated immunoglobulin-like receptor (LAIR) in sera from patients with blistering diseases: possible pathophysiological implications?

Background: Autoimmune Blistering Diseases (AIBD), are a heterogeneous group. Despite their pathogenesis is not completely understood, autoantibodies against directed adhesion molecules of the skin and adjacent mucous membranes could play a key role. The leukocyte-associated-Ig-like-receptor (LAIR) family is a small group of immunoreceptor-tyrosine-based-inhibition-motif-containing inhibitory receptors, recognizing collagens. LAIR-1 is a transmembrane glycoprotein expressed on human-peripheral-blood-leukocytes. LAIR-2 is a secreted receptor mainly produced by CD4+ T-lymphocytes, and is able to regulate the inhibitory potential of LAIR-1. Both LAIRs have been associated with several autoimmune diseases and inflammatory responses. Methods: We evaluated circulating LAIRs in patients with different blistering skin diseases by ELISA. Results: A significant increase of serum LAIR-2, and to a lesser extent of sLAIR-1 (with the exception of Pemphigus vulgaris), in the whole group of patients with bullous diseases, irrespective of the pathogenesis, compared to healthy controls was evident. Conclusions: Although the pathophysiological meaning of LAIR is not completely elucidated, the presence of increased concentration of LAIR proteins can somehow modulate the cascade of inflammatory phenomenon occurring in bullous skin diseases, in different way depending upon specific skin disease considered.