Human IgG subclass pattern of inducing complement‐mediated cytolysis depends on antigen concentration and to a lesser extent on epitope patchiness, antibody affinity and complement concentration

Michaelsen, Terje E.; Garred, Peter; Aase, Audun

doi:10.1002/eji.1830210103

Cited by 165 publications

(119 citation statements)

References 22 publications

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“…As demonstrated here, and by other investigators (24,25), complement concentration is an important factor in complement-mediated cytotoxicity. By increasing the human complement concentration, we were able to recruit the activity of the D270A, K322A, and P329A mutants, which appeared to be completely inactive at FIGURE 6.…”

Section: Discussionsupporting

confidence: 84%

Mapping of the C1q Binding Site on Rituxan, a Chimeric Antibody with a Human IgG1 Fc

Idusogie¹,

Presta²,

Gazzano-Santoro³

et al. 2000

The Journal of Immunology

381

285

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Rituxan (Rituximab) is a chimeric mAb with human IgG1 constant domains used in the therapy of non-Hodgkin’s B cell lymphomas. This Ab targets B cells by binding to the cell-surface receptor, CD20. In our investigation of the mechanism of B cell depletion mediated by Rituximab, we first constructed mutants of Rituximab defective in complement activation but with all other effector functions intact. Our results demonstrate that the previously described C1q binding motif in murine IgG2b constituting residues E318, K320, and K322 is not applicable to a human IgG1 when challenged with either human, rabbit, or guinea pig complement. Alanine substitution at positions E318 and K320 in Rituximab had little or no effect on C1q binding and complement activation, whereas alanine substitution at positions D270, K322, P329, and P331 significantly reduced the ability of Rituximab to bind C1q and activate complement. We have also observed that concentrations of complement approaching physiological levels are able to rescue >60% of the activity of these mutant Abs with low affinity for C1q. These data localize the C1q binding epicenter on human IgG1 and suggest that there are species-specific differences in the C1q binding site of Igs.

show abstract

Section: Discussionsupporting

confidence: 84%

Mapping of the C1q Binding Site on Rituxan, a Chimeric Antibody with a Human IgG1 Fc

Idusogie¹,

Presta²,

Gazzano-Santoro³

et al. 2000

The Journal of Immunology

381

285

View full text Add to dashboard Cite

show abstract

“…Bispecific antibodies capable of binding to two antigens (23) and a chimeric antibody with dual Fc regions (24) were superior to conventional IgG in CMC, presumably because of the increased number of Fc regions and their close arrangement in pairs. A critical number of antigen sites or critical spacing of epitopes on the cell surface has been shown to be necessary for CMC to occur with monovalent IgG (7,25,26). Naturally occurring IgG3 mAbs to carbohydrate antigens, which exhibit intermolecular cooperativity through Fc region interactions, show potent complementmediated effector functions (27).…”

Section: Resultsmentioning

confidence: 99%

Engineered humanized dimeric forms of IgG are more effective antibodies.

Caron

Laird

et al. 1992

The Journal of Experimental Medicine

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SummaryHumanized IgG1 M195 (HuG1-M195), a complementarity determining region-grafted recombinant monoclonal antibody, is reactive with CD33, an antigen expressed on myelogenous leukemia cells. M195 is in use in trials for the therapy of acute myelogenous leukemia. Since biological activity of IgG may depend, in part, on multimeric Fab and Fc clustering, homodimeric forms of HuG1-M195 were constructed by introducing a mutation in the 3'1 chain CH3 region gene to change a serine to a cysteine, allowing interchain disulfide bond formation at the COOH terminal of the IgG. Despite similar avidity, the homodimeric IgG showed a dramatic improvement in the ability to internalize and retain radioisotope in target leukemia cells, Moreover, homodimers were 100-fold more potent at complement-mediated leukemia cell killing and antibody-dependent cellular cytotoxicity using human effectors. Therefore, genetically engineered multimeric constructs of IgG may have advantages relative to those forms that are found naturally.

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“…The vaccine was deoxycholate-extracted OMVs from meningococcal strain 44/76 (B:15:P1.7,16:P5.5:L3,7,9) adsorbed to aluminium hydroxide [19]. Each dose contained 25 mg of protein, 2 mg of lipopolysaccharide (LPS), and 1.67 mg AL(OH) 3 , and was injected in 0.5 ml volumes into the deltoid muscle of human volunteers.…”

Section: Methodsmentioning

confidence: 99%

Opsonophagocytic and Bactericidal Activity Mediated by Purified IgG Subclass Antibodies After Vaccination with the Norwegian Group B Meningococcal Vaccine

Aase

Ea²,

Michaelsen

1998

Scand J Immunol

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Aase A, Høiby EA, Michaelsen TE. Opsonophagocytic and Bactericidal Activity Mediated by Purified IgG Subclass Antibodies After Vaccination with the Norwegian Group B Meningococcal Vaccine. Scand J Immunol 1998;47:388-396 To study how the different immunoglobulin (Ig)G subclass antibodies may confer protection against systemic meningococcal disease, we isolated IgG1, IgG2 and IgG3 antibodies from plasma from vaccinees immunized with the Norwegian meningococcal outer membrane vesicle vaccine. Four IgG1, one IgG2 and four IgG3 preparations were purified. The IgG2 and IgG3 subclass preparations were free from contaminating subclasses, whereas the IgG1 preparations contained from 0 to 14% of IgG2 and/or IgG3. Immunoblotting against whole-cell meningococcal antigens showed broad specificities of the various preparations, both within and between subclasses. These subclass preparations were tested for opsonophagocytic and bactericidal activity. As targets we used two different variants of the meningococcal vaccine strain, with low (44/76-SL) and high (44/76-1) expression of the outer membrane protein Opc. Using polymorphonuclear leucocytes as effector cells in the presence of human complement, all three IgG subclass preparations revealed high, and similar, opsonophagocytic activities against 44/76-SL, whereas against 44/76-1 the IgG2 preparation showed a reduced activity and most IgG3 preparations were slightly more active than the IgG1 preparations. Regarding bactericidal activity, all the three subclasses were highly active against 44/76-SL. Against 44/ 76-1 the bactericidal activities were somewhat more varied: all IgG1 and three IgG3 preparations exhibited higher activities than against 44/76-SL. Due to the low concentration in the IgG2 preparations, only a weak activity was seen against 44/76-1. One IgG3 preparation that was highly opsonophagocytic revealed no bactericidal activity against either of the two bacterial variants examined. In conclusion, we have shown that the IgG subclass effector functions differ from person to person, but that antibodies of IgG1, IgG2 and IgG3 subclasses, judged by their behaviour in the functional tests, may all contribute to protection against meningococcal disease.

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Human IgG subclass pattern of inducing complement‐mediated cytolysis depends on antigen concentration and to a lesser extent on epitope patchiness, antibody affinity and complement concentration

Cited by 165 publications

References 22 publications

Mapping of the C1q Binding Site on Rituxan, a Chimeric Antibody with a Human IgG1 Fc

Mapping of the C1q Binding Site on Rituxan, a Chimeric Antibody with a Human IgG1 Fc

Engineered humanized dimeric forms of IgG are more effective antibodies.

Opsonophagocytic and Bactericidal Activity Mediated by Purified IgG Subclass Antibodies After Vaccination with the Norwegian Group B Meningococcal Vaccine

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