IMMUNOLOGICAL CHARACTERIZATION OF ANTI-ENDOTHELIAL CELL ANTIBODIES INDUCED BY CYTOMEGALOVIRUS INFECTION1

Abstract

We have previously shown that the levels of anti-endothelial cell antibodies (AECA) determined by an enzyme immunoassay are elevated during cytomegalovirus (CMV) infection in cardiac and renal transplant recipients. In a separate study, high levels of AECA are associated with higher frequency of humoral allograft rejection (AR), chronic AR and lower 2 year allograft survival in cardiac transplant recipients. These results suggests that high levels of AECA produced during CMV infection may have a pathogenic role or be a risk factor for humoral AR, chronic AR and decreased allograft survival. Here we examined the reactivity of AECA against endothelial cells and other tissues to further characterize AECA induced by CMV infection. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis/Western blot analysis was performed. The number and intensity of bands reactive with human umbilical vein ECs (HUVECs) increased during and after CMV infection. AECA(+) plasma reacted with multiple antigens expressed not only on endothelial cells but also on human fibroblasts, keratinocytes, platelets (PLs), peripheral blood mononuclear cells (PBMCs), Raji cells and THP-1 cells. Each individual's AECA(+) plasma showed different patterns of reactivity against these cells, whereas each plasma showed similar patterns of reactivity against ECs, PLs or peripheral blood mononuclear cells obtained from different individuals. AECA(+) plasma also showed a similar pattern of reactivity against HUVECs pretreated with/without interferon-γ/tumor necrosis factor-α. The reactivity of preabsorbed sera with PLs significantly decreased against most reactive antigens expressed on PLs and other cell types. (1) Antibodies induced by CMV infection are not specific to endothelial cells and appear to react with multiple cell types, (2) AECA (+) plasma react with multiple antigens expressed on various cell types that are primarily constitutively expressed on these cells and are not individual specific, (3) CMV-induced antibodies in AECA (+) plasma are primarily autoantibodies. These results suggest that the elevated AECA levels seen in CMV-infected transplant recipients may represent a polyclonal activation of humoral immune responses induced by CMV, which is of uncertain pathogenic significance.