To further evaluate the association of anti-entactin antibodies with clinical manifestations in patients with systemic lupus erythematosus (SLE) and related disorders.
Sera were analysed for anti-entactin antibodies from 79 patients with SLE, 38 patients with rheumatoid arthritis, 20 patients with progressive systemic sclerosis and five with Behçet's syndrome. Sera from 150 healthy blood donors and 20 patients with pneumonia were analysed as controls. To study the association of anti-entactin antibodies with severity and activity in SLE, 30 patients were assigned into three groups with 10 patients in each: (1) with mild manifestations; (2) severe disease without renal involvement and (3) frank lupus nephritis. Two blood samples from each patient were analysed, one from the active and the other from the inactive phase of the disease. Additionally, serial sera from 12 patients with SLE were also analysed.
Thirty one patients with SLE (39%) had IgG, IgM or both anti-entactin antibodies. Twenty three of these patients (29%) had biopsy verified glomerulonephritis and 12 (50%) were positive for anti-entactin antibodies. Of the remaining 56 patients without apparent renal involvement, 18 (36%) were positive for anti-entactin antibodies. (chi squared = 2.77, p > 0.05). With the exception of rheumatoid arthritis where six patients (24%) had IgM anti-entactin antibodies, the antibodies were present much less frequently in other diseases (two patients with systemic vasculitis whilst none of the patients with PSS or Behçet's syndrome). Only one patient with pneumonia and none of the 150 sera from healthy blood donors had anti-entactin antibodies. Among Group 1, three (30%) were positive for IgG or IgM anti-entactin antibodies. Six (60%) patients in group 2, and five patients (50%) in group 3 were positive for anti-entactin antibodies. However, the difference between the presence of anti-entactin antibodies between group 1 and 2 or between group 1 and 3 was not significant (p = 0.15 and 0.19 respectively). There was no significant correlation between the titres of anti-entactin antibodies and total serum concentration of IgG (r = 0.141, p > 0.10) and IgM. (r = 0.130, p > 0.10). Furthermore, no significant correlation was observed between SLE disease activity index (SLEDAI) scores and the titres of IgG (r = 0.067, p > 0.10) or IgM (r = -0.033, p > 0.10) anti-entactin antibodies.
The study demonstrates that anti-entactin antibodies are present in a significant number of patients with SLE and tend to be more common in those with severe disease, with or without nephritis, than in patients with mild disease manifestations. There is no correlation between the titre of anti-entactin antibodies and severity or activity of SLE.