Role of autoantibodies to various Ro60 epitopes in the decrease of lymphocytes seen in systemic lupus erythematosus and primary Sjögren's syndrome.

We investigated the roles of autoantibodies to different Ro60 epitopes in lymphopenia in systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (pSS). We recruited 16 patients with SLE, 14 with pSS, and 10 healthy controls; all were female. Patients had active disease, had not received glucocorticoid or immunosuppressants for at least 3 months, and had positive laboratory tests for autoantibodies against Ro60. Patient peripheral blood lymphocyte (LC) counts were < 1 x 10(9)/L: (0.66 ± 0.12) x 10(9)/L and (0.70 ± 0.16) x 10(9)/L for SLE and pSS groups, respectively (P = 0.511). LCs from each group were cultured in vitro with each of the three immunotoxins (ITs) (AE1-3), which specifically combine with one of the three epitopes (aa482-493, aa310-323, and aa230-241, respectively) on Ro60. The cytotoxicity of each IT to the cultured LCs was measured by the MTT colorimetric method. The relationships between IT cytotoxicity and LC counts were analyzed, and autoantibodies against the three epitopes in patient peripheral blood were detected. All ITs showed cytotoxicity to control LCs; however, AE3 and AE2 showed greater toxicity to LCs from SLE and pSS groups, respectively, and the enhanced cytotoxicity was significantly associated with the respective LC counts (r = 0.653, P = 0.06; r = 0.594, P = 0.025). No difference was found in the prevalence of the autoantibodies between the SLE and pSS groups. These results suggest that autoantibodies to Ro60 might play a pathogenic role in lymphopenia in both SLE and pSS, but the pathogenic mechanisms might differ.

Clinical analysis of patients with myeloperoxidase antineutrophil cytoplasmic antibody-associated vasculitis.

This prospective study analyzed the clinical characteristics of myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA)-associated vasculitis and explored the relationship between MPO-ANCA and clinical manifestations of the associated vasculitis in 132 p-ANCA and MPO-ANCA-positive patients (average age, 62.3 ± 14.8 years) who were initially diagnosed with ANCA-associated vasculitis. The p-ANCA and MPO-ANCA levels in peripheral blood were detected in all patients. Among these, 128 (97%) had microscopic polyangiitis (MPA), 3 (2.3%) had granulomatous polyangiitis, and 1 (0.7%) had eosinophilic granulomatous vasculitis. The average time of diagnosis was 10.2 ± 18 months; only 14 (10.6%) patients were diagnosed within 1 month. The main organs involved and the corresponding number of patients were: renal, 95 (72%); lung, 89 (67.4%); joints, 35 (26.5%); heart, 26 (19.7%); peripheral nerve, 23 (17.4%); skin rash, 14 (10.6%); and CNS, 13 (9.8%). Older patients were more likely to show lung involvement in the early disease stage, whereas the joints were involved mostly in the younger patients. The p-ANCA levels (mean titers, 1:60) were not correlated with disease activity and extent of organ involvement, and the MPO-ANCA levels were positively correlated with disease activity, but had no correlation with the extent of organ involvement. MPO-ANCA vasculitis is a common occurrence in China; it mainly involves the elderly and presents as clinical manifestations of MPA. However, the multiple organ damage is not specific leading to delay in diagnosis. MPO-ANCA may play a pathogenic role in the associated vasculitis, and the diverse clinical manifestations might be related with the different characteristics of MPO-ANCA.