Monoclonal antibodies to an immunoglobulin allotype marker G1m(f)

Immunoglobulin allotypes and genetic susceptibility to invasive Haemophilus influenzae type b and Staphylococcus aureus infections in South African children

OBJECTIVE

The purpose of this study was to determine whether the G2m(n), G1m(f) and Km(3) immunoglobulin allotypes have any association with susceptibility to invasive Haemophilus influenzae type b (Hib) and Staphylococcus aureus (S. aureus) infections in children.

METHODS

Direct enzyme-linked immunosorbent assays with commercially available monoclonal antibodies were established to quantitate G2m(n) and G1m(f) allotypes. A qualitative enzyme-linked immunosorbent assay with polyclonal rabbit anti-Km(3) antibody was established for Km(3) determination.

RESULTS

The G2m(n) marker occurred in 34.4% of the mixed ancestry population and 2.9% of the Black population. There was a significantly decreased frequency of the G2m(n) allotype in mixed ancestry children with Hib meningitis (8.5%) and Hib osteomyelitis/septic arthritis and a decreased frequency of Km(3) in black and mixed ancestry children with Hib meningitis. The frequency of G2m(n), G1m(f) and Km(3) allotypes in patients with S. aureus osteomyelitis/septic arthritis were not significantly different from normal population frequency.

CONCLUSIONS

This study shows a clear association between the absence of the G2m(n) allotype in mixed ancestry children and susceptibility to invasive infections caused by H. influenzae and an association between the absence of Km(3) and Hib meningitis in both black and mixed ancestry children.

Assay restriction profiles of three monoclonal antibodies recognizing the G3m(u) allotype. Development of an allotype specific assay

Three monoclonal antibodies raised against a purified human IgG3 paraprotein were found to exhibit a restriction profile for IgG3/G3m(u) and pan-IgG specificity which was dependent on the assay system. When adapted to an IgG3 subclass capture ELISA, all three McAbs discriminated between paraproteins expressing G3m(u) and antithetical markers G3m(st). One of the antibodies (PNF69C) was selected and conditions were optimised for Gm typing purposes. Using this system G3m(u) could be detected on captured IgG3 derived from human sera. This system may prove useful in the elucidation of Gm allotype profiles.

Practical method for production of monoclonal antibody to human IgG allotype G1M F and its applications in ELISAs and dot immunobinding

An anti-G1M F monoclonal antibody was produced by immunization of mice with a single dose of F(ab')2 fragments of normal IgG1-enriched IgG and subsequent fusion of their lymph node cells with P3U1 myeloma cells. Antibody specificity was tested by an ELISA in microtiter plates coated with allotype positive or negative IgG. The usefulness of the antibody as a G1M F typing reagent in inhibition and direct immobilization-type ELISAs and dot immunobinding was demonstrated by re-typing of 100 GM-allotyping control sera. The advantages and disadvantages of these assay methods are discussed.

A miniaturised method for immunoglobulin allotype serology

A modification of the classic haemagglutination inhibition method for immunoglobulin allotyping is described which employs reagent volumes of 2 microliters compared with the 25 microliter volumes commonly used in other serological allotyping methods. No loss of sensitivity or specificity was associated with the miniaturised method when compared to the standard tile technique. This method simplifies the large scale phenotyping and screening of sera and permits considerable savings of valuable reagents to be made.

Improvement in the antibody binding characteristics of microtitre wells by pretreatment with anti-IgG Fc immunoglobulin

A preliminary coating of the surface of polystyrene microtitre wells with anti-IgG Fc immunoglobulin improves the binding capacity of the wells for antibody and leads to a marked improvement in the reproducibility of immunoassays carried out in the wells. In an enhanced chemiluminescent enzyme immunoassay for oestradiol the binding capacity for oestradiol of wells precoated with anti-IgG Fc immunoglobulin and then coated with anti-oestradiol immunoglobulin was more than twice that of wells coated directly with anti-oestradiol immunoglobulin. Intra-assay precision in the precoated wells ranged from 1.3 to 4.0% compared to 2.9 to 6.7% (0-3200 fmol oestradiol) in wells which had not been precoated.