The use of monoclonal subclass-specific antibodies in the investigation of IgG paraproteins in human serum

Monoclonal gammopathies in children

Over a 10-year period sera of 4000 pediatric patients were subjected to agar gel electrophoresis and immunoelectrophoresis. Retrospective examination of the electrophoresis patterns indicated that single or multiple homogeneous immunoglobulin components were present in sera of 155 children (3.9%). They were most frequently found in patients suffering from primary and secondary immunodeficiency diseases, hematological malignancies, autoimmune diseases, and severe aplastic anemia. Follow-up analysis revealed that most of these monoclonal gammopathies were transient. The monoclonal gammopathies in the serum of 79 patients were identified by immunoblotting for class and light-chain isotypes. A marked absence of IgA monoclonal gammopathies and a predominance of monoclonal gammopathies of the lambda light-chain isotype were found. Most of the B-cell mono- or oligoclonal proliferations in children can probably develop due to a disturbance in the regulatory T-cell function.

Dot-immunobinding assay as an accurate and versatile technique for the quantification of human IgG subclasses

A dot-immunobinding assay on nitrocellulose membranes has been developed for the quantification of human IgG subclasses using subclass-specific monoclonal antibodies. The advantages of this technique can be summarized as follows: (1) possibility of rapid semi-quantitative evaluation and/or precise quantitation from the same dot-pattern; (2) simple procedure with very good reproducibility; (3) sensitivity for nanogram concentrations of individual subclasses, therefore applicable not only to serum but also to other body fluids with a low content of IgG; (4) very small amounts of test material needed; (5) very good correlation of results with other techniques (ELISA, radial immunodiffusion) but without some of the inherent problems of the latter methods.

Instantaneous roll-blot from cellulose acetate after electrophoresis. A versatile tool for monoclonal antibody characterization

An instantaneous blotting method from cellulose acetate to nitrocellulose was developed using a high pressure roll apparatus. This method was applied to the early characterization of monoclonal antibody specificity and to monoclonal immunoglobulin typing in mouse hybridoma supernatants, human sera or unconcentrated urines. Immunoglobulins were then revealed using, successively, anti-isotype specific monoclonal or polyclonal antibodies, avidin-biotinylated peroxidase complexes and cobalt-enhanced diaminobenzidine substrate.

Subclass distribution of human myeloma proteins as determined with monoclonal antibodies

Subclasses of 176 IgG and 62 IgA myeloma proteins were determined by indirect ELISA with monoclonal antibodies, as well as by an immunoblotting technique (for monoclonal IgG) and by immunoelectrophoresis against the lectin jacalin (for IgA). The subclass distribution of monoclonal IgG did not reflect mean normal serum levels of the correspondent isotypes, with an over-representation of IgG1 and IgG4 and an under-representation of IgG2 and IgG3 in myeloma. Similarly, IgA2 myeloma were clearly under-represented.