Serological characteristics of systemic lupus erythematosus from a hospital-based rheumatology clinic in Kuwait

Abstract

Thirty-one consecutive patients with SLE were screened for antinuclear antibody (ANA), anti-DNA antibodies, extractable nuclear antigen antibodies (anti-ENAs) including anti-Sm, anti-RNP, anti- SSA (anti-Ro), anti-SSB; (anti-La), anti-Sc1-70, rheumatoid factor (RF), C-reactive protein (CRP), C3 and C4 levels, anti-cardiolipin antibodies (aCL), biologically false positive serological test for syphilis (BF-STS) using VDRL test and Coombs' test. The age of the patients ranged from 11 to 52 year with a median of 29 year; female to male ratio of 5 : 1. There were 21 Kuwaitis, four Egyptians, three from the Indian subcontinent, two Filipinos and one Syrian. Main clinical categories of SLE were: mild cutaneous SLE in 12 (38.7%), clinical antiphospholipid syndrome (APS) secondary to SLE in 8 (25.8%), haematological manifestations of SLE in 5 (16.1%), renal lupus in four (12.9%), neuropsychiatric in three (9.7%), others (6.4%). Clinical features overlapped in several patients. ANA was positive in 96.8% (mean value 891.61 units/ml), anti-DNA in 35.5% (mean value 56.4 units) that was lower than expected and could be due to selection bias as the patients were from a rheumatology clinic, anti-ENA in 42%, anti-Sm 13% that was lower than other non-Caucasian populations, anti-RNP 13%, anti-SS-A in 35.5%, anti-SS-B in 19.4%, Sc1-70 in 13%, CRP in 71% (moderate 58%, very high 13%); C3 mean 1.52 mg/ml (3.2% low levels), C4 mean 0.35 mg/ml (32% low levels), anticardiolipin mean GPL 35.35 units (high 58%), mean MPL 10.61 units (high 26%), BF-STS in 6%, Coombs' test in 6%, RF positive in 36%. The only significant positive clinical associations observed were those of renal involvement with anti-DNA antibodies ( P = 0.042), and clinical antiphospholipid antibody syndrome with aCL antibodies ( P = < 0.05).