Protein HC-IgA complexes carry antibody activities

• Polyclonal protein HC-IgA complexes (HC-IgA) were isolated from two different serum pools. Their hydrodynamic volumes were found to be slightly greater than that of monomeric IgA but less than that of dimeric IgA. Sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis of reduced and carboxymethylated complexes followed by immunoblotting showed that the complexes contained normal light and heavy Ig chains, and one polypeptide chain with Mr = 90,000, which carried both IgA alpha chain and protein HC epitopes. Enzyme-linked immunosorbent assays (ELISA) demonstrated that the isolated HC-IgA carried about 0.1 and 4%, respectively, of the antibody activities against one carbohydrate antigen (Yersinia enterocolitica serotype 0:3 lipopolysaccharide) and one protein antigen (rabbit IgG, i.e. antigen for rheumatoid factors) of the IgA populations of the two serum pools. HC-IgA with rheumatoid factor activity could also be demonstrated in the unfractionated serum pool. The binding of HC-IgA in the ELISA was not mediated through its protein HC part. The present observations show that HC-IgA carries antibody activities and constitutes a unique class of IgA complexes, since it does not dissociate under denaturating conditions after reduction. It may represent a further biological potential of the humoral immune system.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Immunologi inom det medicinska området (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Immunology in the medical area (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Reumatologi och inflammation (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Rheumatology and Autoimmunity (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Mikrobiologi inom det medicinska området (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Microbiology in the medical area (hsv//eng)

Keyword

Alpha-Globulins/isolation & purification

Antibodies/physiology

Enzyme-Linked Immunosorbent Assay

Humans

Immunoglobulin A/isolation & purification

Rheumatoid Factor/immunology

Publication and Content Type

art (subject category)

ref (subject category)