Igg rheumatoid factor in serum of rheumatoid arthritis patients

Rheumatoid arthritis and small airways function. Effects of disease activity, smoking, and alpha 1-antitrypsin deficiency

The sensitive pulmonary function tests of change in maximum expiratory flow (delta Vmax 50) and volume of isoflow were used to determine the effects of rheumatoid arthritis (RA), smoking, and alpha 1-antitrypsin deficiency phenotypes on peripheral airways. Patients were prospectively divided into 4 groups: 14 smokers with RA, 12 nonsmokers with RA, 11 smokers without RA, and 13 nonsmokers without RA. delta Vmax 50 was the most discriminating variable and demonstrated significant small airway obstructive disease in the first 3 groups, with an additive effect in the group of smokers with RA. An increased incidence of the alpha 1-antitrypsin-deficient MS phenotype was seen in the RA smoker group, and this phenotype was associated with severe pulmonary disease.

IgG rheumatoid factor. Detection by enzyme immunoassay in rheumatoid arthritis and normal subjects

IgG rheumatoid factors were demonstrated by enzyme immunoassay using, as antigen, goat antibodies to human serum albumin in the form of immune complexes. Elevated levels of IgG rheumatoid factor were noted in the majority of patients with seropositive rheumatoid arthritis but also relatively often in normal blood donors. Reactivity of IgG rheumatoid factor was in most instances inhibitable by IgG from various species, including man. Exceptionally, restricted specificity towards IgG from bovidae, was recognized.

IgG rheumatoid factor. Relationship to seropositive rheumatoid arthritis and absence in seronegative disorders

IgG rheumatoid factor was detected in the sera of the majority of patients with seropositive rheumatoid arthritis. Values suggestive of IgG rheumatoid factor were noted in one-quarter of patients with seronegative inflammatory arthropathies. These determinations were always low and correlated with elevated IgG concentrations, suggesting nonspecific adherence of IgG rather than a true antigen-antibody reaction. In support of this conclusion, nonrheumatoid factor IgG was capable of concentration-dependent nonspecific adsorption to the solid phase. IgG, but not IgM, rheumatoid factor corresponded with disease activity in patients with seropositive rheumatoid arthritis, suggesting that IgG rheumatoid factor may be important in the pathogenesis.

A simple routine method for detecting hidden rheumatoid factors

A new and simple routine method is described for detecting hidden rheumatoid factors in human serum. EDTA glycine and NaCl were used to liberate hidden rheumatoid factors and to inactivate complement before rheumatoid-factor activity was determined in a glycine--NaCl solution. Forty-nine out of 97 sera from individuals with seronegative rheumatoid arthritis gave positive reactions by this method. Rheumatoid sera with low titres by standard tests gave higher titres with the new method. The new method detects both IgM and IgG rheumatoid factors and is simple and suitable for use in routine medical laboratories. Used in parallel with the classical tests, it facilitates detection of hidden rheumatoid factors.

Estimation of IgM rheumatoid factors by fluorimetry

Sheep red cells coated with rabbit IgG antibody may be used to detect IgM rheumatoid factors either by agglutination or microscopically by the fluorescence of antihuman IgM antibody conjugate bound to rheumatoid factors on the cell surface. By substituting for red cells the plastic surface of a filter disc coated with rabbit IgG it was possible to elute the bound conjugate and measure the fluorescence in a fluorimeter. The results of both the sheep cell agglutination test and the fluorescence test agreed quite well for the majority of sera; both tests seemed to reflect IgM rheumatoid factor concentrations in these sera. The difficulties encountered in attempting to define and measure accurately rheumatoid factor concentrations in a serum are emphasised.