CROSS-REACTIVITY OF AUTOANTIBODIES IN LUPUS AND SCLERODERMA OVERLAP SYNDROMES

Abstract

Lupus-scleroderma overlap syndromes represent a complex subgroup of systemic autoimmune diseases characterized by concurrent clinical and serological features of both systemic lupus erythematosus (SLE) and systemic sclerosis (SSc). This study aimed to investigate the prevalence and cross-reactivity of autoantibodies in patients with SLE, SSc, and lupus-scleroderma overlap syndromes to uncover shared immunological mechanisms contributing to disease overlap. A cross-sectional analysis of 120 patients revealed that individuals with overlap syndromes exhibited significantly high co-positivity for anti-U1RNP (80%), anti-RNP (65%), and anti-Ro/SSA (50%), indicating strong serological convergence. In contrast, anti-dsDNA antibodies were most prevalent in SLE patients (78%), while anti-Scl-70 and anti-centromere antibodies dominated in SSc (60% and 50%, respectively). Cross-reactivity analysis showed a notable overlap in autoantibody pairs, particularly anti-U1RNP with anti-Sm (70%) and anti-RNP with anti-Scl-70 (55%), suggesting functional or structural mimicry between target antigens. Clinically, overlap syndrome patients presented with blended symptoms, including Raynaud’s phenomenon (75%), lupus nephritis (50%), and arthritis (65%), highlighting the diagnostic complexity of these cases. Patients with overlap syndrome tended to be in their forties and had high positivity for ANA antibodies. According to these studies, overlap syndromes are linked to cross-reactive autoantibodies and suggest that patients with mixed autoimmune signs should be examined thoroughly with a variety of serological tests. With this research, experts gain new information that can lead to better identification and treatment of SLE and SSc overlap conditions.