CIRCULATING GROUP-II PHOSPHOLIPASE A(2) ACTIVITY AND ANTILIPOCORTIN ANTIBODIES IN SYSTEMIC LUPUS-ERYTHEMATOSUS - CORRELATIVE STUDY WITH DISEASE-ACTIVITY

Objective. Lipocortin (LC) and phospholpase A(2) (PLA(2)) are involved in phospholipid metabolism, and on the cellular level LC seems to be an antagonist of PLA(2). Since anti-LC1 autoantibodies were found in s ystemic lupus erythematosus (SLE), we undertook a study of the relatio nship between PLA(2), anti-LC1, and disease activity in a large group of patients with SLE. Methods. Sera from 81 patients with SLE were tes ted for the activity of extracellular PLA(2) and the presence and leve l of antilipocortin 1 [anti-LC1 (IgM) and anti-LC1 (IgG)I antibodies. Both were compared to SLE activity. Results. Mean PLA(2) activity was 4.6-fold higher in patients with SLE than in healthy controls (707 +/- 219 vs 154 +/- 6 u/ml, p < 0.01). PLA(2) activity correlated signific antly with PLA(2) immunoreactivity as estimated by an ELISA method usi ng monoclonal antibodies against ''synovial type'' PLA(2) (n = 21, r = 0.984, p < 0.001). Anti-LC1 IgM and IgG antibody levels were signific antly higher in SLE than in healthy individuals [anti-LC1 (IgM) 54.5 /- 4.6 vs 22.6 +/- 2.3 EU/ml, p < 0.001 and anti-LC1 (IgG) 54.3 +/- 3. 4 vs 22.9 +/- 2.3 EU/ml, p < 0.001]. There was no correlation between PLA(2) activity and anti-LC1 antibody titers. Elevated levels of PLA(2 ) [> normal mean + 2 SD (i.e., > 300 u/ml)] were found in 41/81 patien ts with SLE. Anti-LC1 antibody titers were high (> 64 EU/ml) in 23/41 patients; 14/40 patients with SLE with normal PLA(2)0 (<300 u/ml) also had higher titers of anti-LC1 antibodies. PLA, activity was significa ntly associated with the presence of synovitis, being markedly increas ed in 1 1/12 patients. Mean PLA, in this group of patients (1593 +/- 9 57 u/ml) was significantly higher (p < 0.001) than that (553 +/- 188 u /ml) in the group of 69 patients with SLE without synovitis. Conclusio ns. There was no correlation of PLA(2) activity with the Systemic Lupu s Erythematosus Disease Activity Index (SLEDAI) or the Lupus Activity Criteria Count (LACC). Circulating PLA(2) activity in SLE correlated o nly with active synovitis. There was no correlation of anti-LC 1 titer s with duration of the disease, age, steroid dosage, SLEDAI, or LACC o r any individual clinical or laboratory variable included in the asses sment of SLEDAI and LACC.