RESUMEN
The association of rheumatoid factor (RF) and lung disease in several immunologically mediated conditions has suggested that it may be physiopathologically relevant. Since previous reports in hypersensitivity pneumonitis (HP) have dealt mainly with the immunoglobulin M (IgM) RF measurement, we studied such antibody activity in other immunoglobulins, to determine the IgG and IgA RF levels in pigeon-HP, and in asymptomatic breeders (AB) and rheumatoid arthritis (RA) as controls. RFs were measured in 35 HP patients, 41 AB, 31 RA controls, and 55 healthy donors by enzyme-linked immunosorbent assay (ELISA) using human or rabbit immunoglobulin G (IgG), anti-IgM, F(ab')2 of IgG, and IgA F(ab')2 conjugates. An affinity chromatography, fragment crystallizable (Fc) preparations of IgG, pepsin digestion, and Western blots were used to confirm RF specificity. We also evaluated anti-avian antibodies (AA) and cross-reacting antibodies. The HP group revealed positive IgM (51.4%), IgG (31.4%), and immunoglobulin A (IgA) (34.2%) RF tests, and these antibody values exceeded the AB reference levels (P<0.02). HP and RA showed a similar frequency and distribution of RFs. Possible immunoassay interferences were excluded. As in other immunologically mediated diseases, IgG and IgA RFs may play a pathogenic role in HP, amplifying the inflammatory reaction, immune-complex formation, and complement activation. IgM-RF producing cells that have been implicated in the presentation of self and foreign antigens, and T-cell activation might induce the isotype switching of RFs.
Asunto(s)
Pulmón de Criadores de Aves/inmunología , Inmunoglobulina A/inmunología , Inmunoglobulina G/inmunología , Inmunoglobulina M/inmunología , Factor Reumatoide/sangre , Adulto , Pulmón de Criadores de Aves/sangre , Femenino , Humanos , Masculino , Factor Reumatoide/clasificaciónRESUMEN
Hidden 19S IgM rheumatoid factor (RF) and 7S IgG RF were assayed in 24 children with juvenile chronic arthritis (JCA) and 26 controls, in whole sera and in the IgM and IgG containing fractions of the serum after separation by acid gel filtration. When non-fractioned serum was used, IgM RF detection was positive in 4.2% by latex fixation test and 4.2% by ELISA. IgG RF was positive in 91.7% by ELISA. In the IgM containing fraction of the serum, the positivity for IgM RF was 41.7% by LFT and 54.2% by ELISA. In the IgG containing fraction the positivity for IgG RF was 100%. These results suggest toward the need of previous serum dissociation before hidden 19S IgM RF is assayed and demonstrate high prevalence of 7S IgG RF.
Asunto(s)
Artritis Juvenil/inmunología , Cromatografía en Gel , Inmunoglobulina G/sangre , Inmunoglobulina M/sangre , Factor Reumatoide/sangre , Adolescente , Complejo Antígeno-Anticuerpo/sangre , Artritis Juvenil/sangre , Niño , Preescolar , Ensayo de Inmunoadsorción Enzimática , Reacciones Falso Negativas , Femenino , Humanos , Concentración de Iones de Hidrógeno , Masculino , Peso Molecular , Factor Reumatoide/clasificación , Sensibilidad y EspecificidadRESUMEN
Sera from 24 children with Henoch-Schönlein purpura (HSP) and 25 controls were tested for rheumatoid factor (RF) of various isotypes. None of the patients with HSP had RF of the IgG or IgM isotypes, whereas one of the controls had IgG RF and one had IgM RF. On the other hand, IgA RF was found in 13 (54%) of the HSP sera, but in only one of the controls (P less than 0.005). The IgA RF showed some cross-species reactivity, but it generally reacted better to human IgG than to rabbit IgG (P less than 0.01) or goat IgG (P less than 0.005). The mean serum IgA concentration was higher in IgA RF positive patients (245 +/- 92 mg/dl) than in IgA RF negative patients (171 +/- 69 mg/dl) (P less than 0.05). Moreover, there was a positive correlation between IgA RF concentration and the level of serum IgA above the mean concentration for age (P less than 0.05). When present, IgA RF concentration tended to be highest during the acute phase of the illness, but there was no correlation between IgA RF and the severity or duration of HSP. These results add to the growing list of immunologic abnormalities in HSP and suggest that IgA RF production may be linked to a basic disturbance of IgA production in HSP.