Production of anti-endothelial cell antibodies by coculture of EBV-infected human B cells with endothelial cells

Activation of the immune system and coronary artery disease: the role of anti-endothelial cell antibodies

On the basis of the role of immuno-mediated inflammation in atherosclerosis we investigated, (1) the prevalence of anti-endothelial cell antibodies (AECA) in ischaemic heart disease (IHD); (2) if beta2-glycoprotein I (beta2-GPI) was the target antigen of AECA; (3) the relationship between AECA, tissue factor (TF) and tissue factor pathway inhibitor (TFPI). In 93 consecutive IHD patients undergoing percutaneous transluminal coronary angioplasty (PTCA) and 105 controls AECA were detected by ELISA on human umbilical vein endothelial cells (HUVEC). AECA positive sera were evaluated for anti-beta2-GPI antibodies by ELISA. TF and TFPI plasma levels were assessed by ELISA. Twelve of 93 (12.9%) IHD patients and only one of 105 controls (0.95%) were AECA positive. The prevalence of AECA was higher in unstable angina (UA) than in effort angina (EA) (P=0.01). Three of 12 AECA positive sera resulted positive for anti-beta2-GPI and showed a marked decrease in EC-binding when tested on HUVEC cultured in serum-free medium. The binding was restored by the addition of beta2-GPI. TF and TFPI levels were similar in AECA positive and AECA negative patients. The rate of angiographically documented clinical recurrences was 66.7% in the AECA positive and 14.8% in the AECA negative group (P=0.0004) with a significant relationship between restenosis and AECA (P<0.0001), unchanged by the inclusion of cardiovascular risk factors in the regression model. Our results suggest a 'role' for AECA in the immune-mediated inflammation in UA beta2-GPI is not the only AECA target antigen. AECA are not responsible for high TF and TFPI levels. The high rate of clinical recurrences after PTCA, confirmed by angiography, in AECA positive patients is in line with such a role and suggests further large-scale 'ad hoc' studies.

Antibodies to endothelial cells in borderline hypertension

BACKGROUND

Antibodies to endothelial cells (aECs) and to cardiolipin (aCLs) are implicated in autoimmune diseases like systemic lupus erythematosus vasculitis. Beta2-Glycoprotein 1 (beta2GP1) is a cofactor for aCLs. The present study investigated the possible role of aECs, aCLs, and abeta2GP1 in borderline hypertension.

METHODS AND RESULTS

Seventy-three men with borderline hypertension (BHT) and 73 age-matched normotensive (NT) men (diastolic blood pressure, 85 to 94 and <80 mm Hg, respectively) were recruited from a population screening program. Antibody levels were determined by ELISA. Presence of carotid atherosclerosis was determined by B-mode ultrasonography, and 29 individuals had atherosclerotic plaques. BHT men had significantly higher aEC and abeta2GP1 levels of IgG class than NT control subjects (P=0.029 and P=0.0001, respectively). aEC levels of IgM class were higher in BHT (P=0.012), but not abeta2GP1 levels. There was no correlation between aCL levels and BHT. Individuals with atherosclerotic plaques had significantly higher aEC levels of both IgG (P=0.042) and IgM subclasses (P=0.018) than those without plaques, but no difference was found in aCL and abeta2GP1 levels. Endothelin and aECs of IgM class were significantly associated.

CONCLUSIONS

We demonstrate the first evidence of a significant elevation of aEC and abeta2GP1 levels in borderline hypertension. These findings provide a new link between hypertension and atherosclerosis and indicate that humoral immune reactions to the endothelium may play an important role in both conditions.

Novel autoantibodies against muscle-cell membrane proteins in patients with myositis

OBJECTIVE

To search for autoantibodies against muscle cell-specific surface membrane antigens in patients with inflammatory myopathies.

METHODS

A cell enzyme-linked immunosorbent assay (cell ELISA) using a human rhabdomyosarcoma cell line (TE-671) was developed and performed in serial dilutions with either nonfixed or fixed cells. A total of 141 different patient sera were tested: 90 from patients with various rheumatic diseases, 12 from patients with cardiomyopathies, 25 from patients with other muscular diseases, and 14 from patients who had undergone major surgery or who had other noninflammatory diseases. As controls, 20 sera were obtained from healthy donors. Results were correlated using immunofluorescence staining and flow cytometry.

RESULTS

Using the nonfixed cell ELISA, the proportions of positive sera from the patient groups with rheumatic diseases were 71% with polymyositis (PM), 15% with dermatomyositis (DM), 18% with systemic sclerosis (SSc), 15% with systemic lupus erythematosus (SLE), and 7% with rheumatoid arthritis. Sera from healthy donors, as well as sera from patients with nonrheumatic diseases, did not show significant reactivities. When other cell lines, including a chondrosarcoma, a bladder carcinoma, a pancreas carcinoma, and human foreskin fibroblasts, were used as substrates, positive sera did not react in the cell ELISA. Results obtained with the cell ELISA system using nonfixed cells were confirmed by flow cytometry and immunofluorescence staining. A strong protein band of 50 kd was detected on plasma membrane preparations from TE-671 muscle cells in 33% of PM sera (n = 12).

CONCLUSION

In most sera from patients with PM, DM, and some other rheumatic diseases (i.e., SSc and SLE), autoantibodies directed against muscle-cell surface antigens can be detected. Since these molecules are localized in the muscle-cell surface membrane, autoantibodies directed against these antigens could play a major role in the pathogenesis of PM.