[Antineutrophil cytoplasmic antibodies in patients with diffuse diseases of connective tissue]

To investigate the significance of antibodies against neutrophil cytoplasmic antigens (ANCA) in patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and systemic sclerosis (SS), their relations with the syndromes and laboratory indices.

The sera from 277 patients suffering from connective tissue disease and 31 healthy persons were examined. Of patients, 103, 126 and 48 had RA, SLE and SS, respectively. The patients in each group were subdivided into ANCA positive (ANCA+) and ANCA negative (ANCA-). The patients were matched within the groups by age, sex and disease duration. There were 41 such pairs in RA group, 23 in SLE and 13 in SS group. Questionnaires and laboratory tests (ANA, RF, a-DNA, a-MPO, a-Scl-70, a-PR3, a-CL) were used in the examination.

The sensitivity of ANCA in SLE patients group was as high as 58.7%, specificity--93.5%. In other groups ANCA were less frequent. ANCA were significantly associated with skin vasculitis and ANA prevalence but the disease activity in SLE was not related to this feature. Anemia and antibodies against cardiolipin were found significantly more frequently in ANCA positive RA group. In SS group the inverted clinical association with kidney damage was seen but a-DNA were more prominent in ANCA+ group. Subspecificity for a-MPO and a-PR3 and lactoferin by ELISA were revealed less often than a-ANCA by immunofluorescence. Only two SLE patients with a-lactoferin antibodies were evidently different in prognosis while the other ones did not differ in the disease course within their group.

The ANCA pattern in connective tissue diseases is found rather often but only few clinical and laboratory associations could be established such as skin vasculitis and ANA domination in SLE group, anemia and a-CL in RA group and a-DNA in SS ANCA+ groups. The validity of ANCA test is not so significant as it is in vasculitis patients.