Anti-neutrophil cytoplasmic antibodies (ANCA): Their usefulness in autoimmune vasculitis prognosis

Using the indirect immunofluorescence technique (IFI) as screening test, the association between anti-neutrophil cytoplasmic antibodies (ANCA) and several clinical disorders was established. The antigenic specificity was also determined by enzymoimmunoassay (EIA). The relatioship between the immunoglobulin isotipes involved and clinical features were studied. Serums of 246 patients were studied, 102 with confirmed diagnosis of vasculitis, connective tissue disease or renal disorders. Another group of 142 patients, was included, with several diseases that involve or may involve organs and systems in the same way as immune vasculitis. From the overall samples, 29 were reactive by IFI, 16 of them were further studied using EIA, giving 14 positive reactions: ANCA were detected in 8/11 (73 %) serum of patients with Wegener granulomatosis (WG), 7 of them were cANCA (87,5 %) and 1 pANCA. In Systemic Lupus Erythematosus (SLE), 4/32 (12.5 %) were ANCA positive (1 cANCA and 3 pANCA), and in Politarteritis Nodosa (PAN) 618 (75 %) were pANCA positive. After studying the relationship between cANCA and different illnesses or patients with clinical features related with vasculitis, only a significant association (p < 0.01) with GW was found. In a group of patients with SLE, PAN, autoimmune hepatitis (3/8), renal insufficiency of unknown etiology (3/7), pANCA pattern was significant associated (p < 0.01) to these diseases, when compared with the rest of ANCA positive samples. The PR3 antigen was associated 1/1 with cANCA and 1/1 pANCA, 12/16 MPO gave pANCA pattern and 2/12 pANCA given no reaction with the studied antigens. The association between IgG ANCA and other isotypes studied in the total number of patients was not significant (p > 0.01). In three cases that were positive for IgG and IgM ANCA a correlation was found between their simultaneous presence and the degree of renal damage. The systematic ANCA study, particularly the antigenic specificity, would add criteria to illness prognosis and evolution. It would also help to understand the vasculitic phenomena in several illnesses.