A study of immunological profile, disease characteristics and socioeconomic status of a population of rheumatoid arthritis patients in Sri Lanka

Abstract

Objective To study the immunological profile, disease characteristics and socioeconomic status of a population of patients with rheumatoid arthritis (RA) in Sri Lanka. Methods A case-control study was undertaken to characterize the immunoglobulin profiles of 105 RA and, age and gender matched osteoarthritis (OA) patients ( n = 30) from the National Hospital, Sri Lanka. Healthy, non-arthritic individuals ( n=30) served as controls. Sera were assayed for immunoglobulins [IgG, IgM, IgE and IgA isotypes] by establishing sandwich type ELISA. IgM, IgG and IgA rheumatoid factors (RFs) of 162RA patients were assayed by indirect ELISA. Disease characteristics and socioeconomic factors were accrued via an interviewer-administered questionnaire. Results Higher IgG, IgM, IgE, IgA and lower IgG1, IgG2 levels were observed in RA sera compared with controls ( P < 0.05). Novel correlations between disease characteristics and immunoglobulins, as well as group-specific correlation matrices of immunoglobulins and RFs ( P < 0.05) of seropositive and seronegative patients, were found. Higher IgM-RF and IgA-RF levels in seropositives and IgG-RF in seronegatives were evident compared with controls ( P < 0.05). Immunoglobulin and RF profiles did not reflect gender disparity of RA ( P > 0.05). Proportions of seropositives with nodules and erosions were significantly higher than seronegatives ( P < 0.05). While IgM-RF and erosions positively correlated in the seropositives ( P < 0.05), the seronegatives showed an inverse correlation between IgG-RF and erosions ( P < 0.01). Familial clustering imposed a relative risk of 4.7 for developing seropositive RA. Conclusions This model study provides baseline information on pathogenetic aspects of RA in Sri Lanka, which may have implications for further research on management of the disease.