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In children with a nonspecific constitutional presentation such as prolonged fever, the physician should pay attention to primary vasculitides after ruling out the more common diseases such as infectious diseases, malignancies, and the other rheumatic disorders. The past history of autoimmunity may be a clue for this.

ResumenLas Vasculitis Primarias son enfermedades poco frecuentes, potencialmente fatales, sin causa etiológica conocida, que pueden comprometer a vasos sanguíneos de distinto tamaño, produciéndoles un proceso inflamatorio en la pared vascular, que conduce a la estrechez u obstrucción del vaso afectado, con consecuente isquemia o necrosis del tejido que irrigan. Sus manifestaciones clínicas pueden ser muy variadas, y frecuentemente inespecíficas. Sin embargo hay algunas que hacen sospechar el diagnóstico y que deben ser evaluadas con detalle.El estudio diagnóstico de las vasculitis primarias, implica varios aspectos que deben ser considerados. La actividad, la extensión, el daño visceral y el diagnóstico diferencial. En este sentido los exámenes bioquímicos; los exámenes funcionales organicos; los estudios de imágenes (radiológicos, tomografía computarizadas, resonancia magnética, radio isotópicas, y de Pet -CT); y la histopatología (biopsias de riñón, sistema nervioso periférico, pulmonar, etc.); y los estudios de autoanticuerpos (muy especialmente los ANCA, en vasculitis de pequeño vaso) ayudan a fundamentar el diagnóstico definitivo.Su tratamiento debe considerar dos etapas. Inicialmente la terapia de inducción de la remisión, y luego de lograrla, la de mantenimiento de la remisión. De la naturaleza de la vasculitis y del éxito que se logre con el tratamiento, dependerá su pronóstico.Las drogas tradicionales, más usadas en el tratamiento, y habitualmente más efectivas, son los corticoesteroides (orales o EV en bolos) y la ciclofosfamida (oral o preferentemente en bolos EV). Tambien se han usado la Azatioprina, el metotrexato, y el micofenolato mofetil, especialmente como mantenimiento de remisión. En los últimos años, se ha destacado el uso de terapia biológica, con anticuerpos monoclonales anti lifocitos B, el Rituximab, que resulta de gran utilidad, muy especialmente en las vasculitis de pequeño vaso ANCA positivo.El diagnóstico diferencial incluye patologías muy diversas; trombosis ateroesclerótica; embolias ateroescleróticas, embolias sépticas, el uso de drogas ilícitas, y la trombosis secundaria al Sindrome Antifosfolípido.SummaryPrimary vasculitis is an infrecuent desease, and may present in very different clinical pictures.Any size of blood vessels can be affected (aorta, large it; arteries, médium -size, and small), it may be produced by immunological tissue damage mechanisms.Classification of primary vasculitis usually consider both aspects.Histopathology includes, giant cells large vasculitis; granulomatous aortitis; systemic inflamatory necrotizing and segmentary médium size arterities;Granomalous necrotazing small vessel vasculitis, with or without eosinofilic infiltration; and leucocitoclastic small vessel vasculitis.Clinicians should be awared of this deseases in order to diagnose promptly and do a proper therapy.

Polymorphonuclear neutrophils in Wegener's granulomatosis acquire characteristics of antigen presenting cells. Background Constitutive expression of major histocompatibility complex (MHC) class II antigens and of the co-stimulatory receptors CD80 and CD86 is restricted to professional antigen presenting cells. Polymorphonuclear neutrophils (PMN) of healthy donors are negative for those antigens. Our recent study, however, found that PMN of patients with active Wegener's granulomatosis acquired MHC class II antigens. Methods To continue and extend the previous study results, PMN and monocytes of 60 patients with Wegener's granulomatosis, 24 patients with microscopic polyangiitis (MPA), 20 patients with acute bacterial infection, and 53 healthy donors were analyzed for the expression of MHC class II antigens as well as of CD80 and CD86. Moreover, induction on PMN of MHC class II expression was studied, as was antigen presentation as a possible functional consequence. Results PMN of patients with acute, active Wegener's granulomatosis expressed MHC class II antigens, CD80 and CD86; on monocytes up-regulation of MHC class II was seen. In contrast, PMN of patients with inactive disease, or with relapse, patients with microscopic polyangiitis or with bacterial infections expressed neither MHC class II, nor CD80 or CD86. PMN of healthy donors acquired these antigens when cultured in the presence of T cells or T cell-derived cytokines. The PMN were then able to present to T cell antigens in a MHC-class II restricted manner. Conclusion During active disease, the PMN of patients with Wegener's granulomatosis acquire characteristics of antigen presenting cells, whereas the PMN of patients with MPA or bacterial infection do not. The finding reflects differences in the pattern of the respective inflammatory response and suggests new effector functions of PMN. Moreover, MHC class II expression on PMN could serve as a novel marker for active Wegener's granulomatosis.

Wegener's granulomatosis is associated with organ-specific antiendothelial cell antibodies. Background Antiendothelial cell antibodies (AECA), usually detected using human umbilical vein endothelial cells (HUVEC), are frequently observed in systemic vasculitis, but their pathogenic role is unclear. Heterogeneity of endothelial cells necessitates use of clinically relevant endothelial cells for elucidation of the role of AECA in systemic vasculitis involving small blood vessels of specific organs. Methods Human endothelial cells were isolated from normal tissue specimens from the nose, kidney, lung, liver, and umbilical vein. Using flow cytometry, AECA were detected against both unstimulated and cytokine-stimulated [tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ)] endothelial cells. Functional capacity of AECA was determined by complement fixation assay. Sera from patients with Wegener's granulomatosis (16), limited Wegener's granulomatosis (8), renal limited disease (4), microscopic polyangiitis (MPA) (5), rheumatoid arthritis (10), and systemic lupus erythematosus (SLE) (9), and from healthy controls (20) were analyzed. Results Compared with controls ( 1 ) Wegener's granulomatosis is significantly associated with noncytotoxic AECA that selectively bind surface antigens on unstimulated nasal, kidney, and lung endothelial cells; ( 2 ) binding of Wegener's granulomatosis AECA to kidney and nasal endothelial cells in particular was lost upon treatment with IFN-γ and TNF-α; ( 3 ) the two cytokines per se were cytotoxic (30%) to nasal and lung endothelial cells and lysis was further increased (60%) by addition of systemic vasculitis serum; and ( 4 ) Wegener's granulomatosis serum caused agglutination of cytokine-stimulated nasal endothelial cells. Conclusion Based on these findings we suggest that AECA may be one factor involved in the initiation of Wegener's granulomatosis. Antigen identification and elucidation of the pathogenic roles of AECA and inflammatory cytokines in systemic vasculitis using these cells will be particularly important.