Effect of cytomegalovirus infection and leukocyte immunoglobulin like receptor B1 polymorphisms on receptor expression in peripheral blood mononuclear cells.

Leukocyte immunoglobulin like receptor B1 (LILRB1) is a receptor with a significant role in several infectious, autoimmune, cardiovascular, and oncologic disorders. LILRB1 expression varies between individuals and may be associated to polymorphisms on the regulatory region of the LILRB1 gene, as well as to previous cytomegalovirus infection. We analyzed the contribution of these two factors to LILRB1 expression in peripheral blood mononuclear cells of healthy young adults. LILRB1 expression in NK cells, T cells, B cells, and monocytes was significantly higher in subjects with previous cytomegalovirus infection than in those without infection (P < 0.001, P < 0.001, P < 0.01, and P < 0.001, respectively). Overall, no differences in LILRB1 expression were observed between individuals with and without GAA haplotypes of the LILRB1 regulatory region. However, when analyzed according to cytomegalovirus infection status, significant differences in LILRB1+ NK cells were observed: a higher proportion of LILRB1-positive cells was found in GAA+ individuals compared to GAA- individuals in the absence of infection (P < 0.01), but GAA- individuals showed a larger proportion of LILRB1-positive cells than GAA+ subjects in cytomegalovirus positive individuals (P < 0.01). In conclusion, cytomegalovirus infection is a major factor affecting LILRB1 expression in NK and other mononuclear cells, while polymorphisms in the LILRB1 regulatory region appear to have a modulatory influence over this effect.