IgG antigens of the C gamma 2 and C gamma 3 homology regions interacting with rheumatoid factors.

Haemagglutination inhibition experiments were used to study the interaction of several well-defined rheumatoid factors with pFc' fragments (≡Cγ3 homology regions) prepared from all four IgG subclasses. The results suggest that rheumatoid factors interact with antigens located in both homology regions of the Fc fragment. A minimum of four reactive regions is suggested—one in the Cγ3 region and three more in the Cγ2 region.

Immunglobulin classes, subclasses and complexes of IgG rheumatoid factor in rheumatoid plasma cells.

The different immunoglobulin classes, IgG subclasses and types of light chains in plasma cells of thirty-four rheumatoid synovial membranes were studied. In some of these membranes a particular Ig class or IgG subclass was selectively concentrated, indicating local production of antibodies. Large amounts of plasma cells containing IgG were detected in all tissues.

Lymphocytes with membrane-bound immunoglobulin (B-lymphocytes) in new-born babies.

Lymphocytes with surface-bound immunoglobulins (B-lymphocytes) were detected in cord blood of normal babies by means of immunofluorescent staining of viable cells. The mean value of Ig-positive lymphocytes was 14·3% (range 5–33%). IgM was found on the highest percentage of lymphocytes (mean 9·7%), but IgG was also found in a considerable proportion (mean 7·9%).

Class, subclass, and allelic exclusion of membrane-bound Ig of human B lymphocytes.

Membrane-bound immunoglobulins of peripheral blood B lymphocytes and of lymphocytes from an IgG chronic lymphocytic leukemia showed restriction to one immunoglobulin class, one IgG subclass, and one Gm allotype. Certain antigens in the C-terminal part of IgG Fc were not exposed on the cell surface.

Immunological characterization of amyloid fibrils in tissue sections.

The labelling of rabbit antiserum against purified and alkaline-degraded amyloid fibrils with fluorescein isothiocyanate (FITC), has enabled the detection of amyloid deposits in various tissue sections by direct immunofluorescence. There was antigenic identity between amyloid from different organs of the same patient. In addition, indirect immunofluorescence revealed individual antigenic specificity and cross-reactivity among amyloid from different individuals.

Individual antigenic specificity and cross-reactions among amyloid preparations from different individuals.

Amyloid fibrils were isolated from eleven amyloid-laden organs of six patients. By alkaline degradation, soluble units were obtained which gave antibody formation in rabbits. Gel precipitation and haemagglutination inhibition were used to characterize antigens of the amyloid.