Laboratory of Clinical Immunology, Department of Molecular Biology, Immunology and Medical Genetics, Faculty of Medicine, Thracian University, Stara Zagora, Bulgaria.
AIM: To study the prevalence of antineutrophil cytoplasmic antibodies against lactoferrin in patients with connective tissue diseases and to characterize the antibody response to lactoferrin in these patients. METHODS: Sera from 60 patients with systemic lupus erythematosus, 98 with rheumatoid arthritis, 11 with systemic sclerosis, and 6 with mixed connective tissue disease were studied. The presence of anti-lactoferrin antibodies was detected by enzyme-linked immunosorbent assay. The IgG subclass reactivity of antibodies to lactoferrin was analyzed by biotin-extravidin amplified enzyme-linked immunosorbent assay and monoclonal antibodies to human IgG subclasses. RESULTS: Anti-lactoferrin antibodies were found in 15 patients (5 patients with rheumatoid arthritis and 10 with systemic lupus erythematosus). IgG1 was the predominant subclass for antibodies to lactoferrin. CONCLUSION: Patients with connective tissue diseases are known to develop multiple auto-antibodies; anti-lactoferrin antibodies mainly of IgG1 isotype can also be found in patients with rheumatoid arthritis and more often in patients with systemic lupus erythematosus.