[Antinuclear antibodies, patterns and characteristics obtained by immunofluorescence. The importance of the IgA, IgM and IgG isotypes].
The indirect immunofluorescence with epitelial cell line from human laryngeal carcinoma as substrate (IIF-HEp2) and anti-IgG or anti-total Ig as antisera, is the technique currently used for the detection of antinuclear antibodies. The most important antibodies for the diagnosis and follow-up of connective tissue diseases (CTD) are the IgG-ANA, while the IgM-ANA have no clinical relevance. However the IgA-ANA have not been thoroughly investigated so far. The aim of this work was to study the prevalence of different ANA isotypes of Ig antibodies in CTD patients and to evaluate the convenience of the use of monovalent or polyvalent conjugate. We examined the sera of 100 patients with different CTD by IIF-HEp2 and detected a prevalence of 38% IgA-ANA (titles > or = 1:80) and 12% IgM-ANA (titles < or = 1:160). In twenty nine cases we detected IgA-ANA in absence of IgM-ANA, and in 3 cases IgM-ANA in absence of IgA-ANA. In all the cases IgG-ANA were present. In 6 sera a change in the immunofluorescence pattern was observed while using anti-IgA conjugate, whereas in 3 the change was observed with the use of anti-IgM conjugate. Because of the high prevalence of ANA-IgA detected by IIF-HEp2, we emphasize the convenience of employing anti-total Ig in spite of anti-IgG conjugated until the role of ANA-IgA is dilucidated in CTD patients, in order to establish its relevance in the diagnosis, prognosis and follow-up of systemic rheumatic diseases.
Arcavi
Miriam
M
Laboratorio de Inmunología Clínica, Departamento de Bioquímica Clínica, Facultad de Farmacia y Bioquímica, Hospital de Clínicas José de San Martín, Universidad de Buenos Aires. arcavimiriam@hotmail.com
Dadone
Jorge
J
D000974:Antibodies, Antinuclear / Q000097:blood / Q000276:immunology*; D003240:Connective Tissue Diseases / Q000175:diagnosis / Q000276:immunology*; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood / Q000276:immunology; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007132:Immunoglobulin Isotypes / Q000097:blood / Q000276:immunology*; D007075:Immunoglobulin M / Q000097:blood / Q000276:immunology; D012189:Retrospective Studies
D000974:Antibodies, Antinuclear; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007132:Immunoglobulin Isotypes; D007075:Immunoglobulin M