[Antineurotrophil cytoplasmic antibodies (ANCA) in the elderly]

Aging in animals and human beings is frequently accompanied by a disarray of the immune response. In subjects 70 years of age or older the frequency of some autoantibodies (anti-nuclear, RF, antithyroid anti-parietal cell and others) without any associated pathology is clearly increased when compared against a younger population. ANCA (antineutrophil cytoplasmic antibodies) is considered to be a good marker for necrotizing systemic vasculitis. This auto-antibody is known to show two patterns when investigated by indirect immunofluorescence on alcohol fixed normal neutrophils: c-ANCA (cytoplasmatic fluorescence) and p-ANCA (perinuclear fluorescence), each one associated with different pathologies. The purpose of this work was to investigate how frequently was ANCA found in subjects 70 years of age or older without evidence of any associated pathology. ANCA was investigated in 447 ambulatory patients from our hospital and the only requirement to be included was age. The ANCA+ patients were divided into having or not clinical suspicion of vasculitis, according to the medical charts we reviewed. The same methodology was applied to investigate the frequency of antinuclear antibodies (ANA+) without clinical evidence of any associated pathology. This frequency was compared with that described in the literature as "ANA+ in healthy old subjects". In the 447 patients studied, 8 were positive for ANCA (1.8%), 3 for c-ANCA and 5 for p-ANCA. None of the 3 c-ANCA and only 1 of 5 p-ANCA belonged to patients without any associated pathology. A possible relationship between c-ANCA and cancer is discussed. As ANCA+ cases were very few no relationship with gender or age was investigated. The extremely low finding of ANCA+ in the absence of pathology, even considering old people's frequent immunological disarray suggests that in opposition to other autoantibodies, the presence of ANCA is always related to disease. The frequency of ANA+ without associated pathology was 2.9%, being this value on the lower limits of what is described in the literature. This can be due to different methodology or to the scope of the definition of "without associated pathology".