Human IgG2 Can Form Covalent Dimers

Yoo, Esther M.; Wims, Letitia A.; Chan, Lisa A.; Morrison, Sherie L.

doi:10.4049/jimmunol.170.6.3134

Cited by 123 publications

(112 citation statements)

References 43 publications

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“…Additionally, we cannot rule out the possibility that NIB (28SA)-G2 exhibited cooperative binding to cell surface CD28. Such cooperativity in cocultures could occur through dimer formation involving one or more of the hinge region cysteines (52) and mimic increasing density of mAb presentation when immobilized on plastic where markedly sigmoidal dose-responses were also observed. Although we did not detect significantly different levels of dimer in NIB(28SA)-G2 compared with the other mAbs after SE-HPLC or covalently linked IgG2 dimer using SDS-PAGE (B.…”

Section: Responses Of Pbmcs To Nib(28sa)-g4 Nib(28sa)-g1 and Nib(28mentioning

confidence: 99%

Antibody C Region Influences TGN1412-like Functional Activity In Vitro

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Fox

Hufton

et al. 2012

The Journal of Immunology

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The unexpected outcome of the clinical trial of the superagonistic CD28 mAb TGN1412 (IgG4κ) continues to stimulate interest. We show that TGN1412 binds similarly to human and cynomolgus macaque FcγR, eliminating the possibility that differences in Fc-mediated interactions with FcγR contributed to the failure of preclinical testing in macaques to predict toxicity in humans. The influence of the Fc domain and C region structure on the in vitro functional activity of TGN1412 was investigated using F(ab′)2 and Fab fragments derived from TGN1412 recovered from the trial and recombinant TGN1412 subclass variants and mutants. Superagonistic activity, as measured by cytokine release and proliferation, was assessed by exposing PBMCs to immobilized mAbs/fragments or to aqueous mAbs/fragments in the presence of HUVEC monolayers. Removing the Fc generally curtailed or abolished PBMC activation. However, eliminating detectable FcγR-binding of the IgG4 by mutation (L235E) did not abrogate activity. Stabilizing the “wild-type” IgG4 hinge (S228P) enhanced activity without increasing FcγR binding, which could only partially be explained by inhibition of Fab arm–exchange. Subclass switching the IgG4 mAb to IgG1 decreased activity, whereas switching to IgG2 markedly increased activity. We conclude that the C region strongly influences in vitro CD28-mediated superagonistic signaling. Superagonism requires an intact Fc, as shown by the absence of activity of TGN1412 Fab and F(ab′)2 fragments, but, notably, appears to be relatively independent of FcγR-binding properties. We propose that the Fc, potentially through restricting flexibility, maintains a favorable V region conformation to allow superagonistic activity. These findings have important implications for Ab design strategies.

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Section: Responses Of Pbmcs To Nib(28sa)-g4 Nib(28sa)-g1 and Nib(28mentioning

confidence: 99%

Antibody C Region Influences TGN1412-like Functional Activity In Vitro

Ball

Fox

Hufton

et al. 2012

The Journal of Immunology

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“…The observed underestimation of the monoclonal protein could then be explained by self-aggregation of truncated heavy chains. This self-aggregation is well recognized for IgM and IgA, but cases of covalent polymers of IgG have also been described (8 ). It is also possible that the antisera we used for typing the subclasses could have contained antibodies that recognized domains that were absent from the patient's truncated IgG, because these antisera were obtained from sheep that had been immunized against human IgG1, IgG2, IgG3, and IgG4.…”

Section: Discussionmentioning

confidence: 99%

Unusual Increased β-Globulins in an Elderly Patient

et al. 2011

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A 90-year-old man who had a history of transurethral prostate resection for benign prostatic hyperplasia was admitted for left hip pain. A hip radiography examination revealed a large osteolytic lesion in the left greater trochanter, and a bone scintigraphy evaluation showed increased activity in the same area. Because of the patient's history, metastasis from prostate carcinoma was suspected, and bone biopsies were performed the same week. Ten days later, the patient was hospitalized in the emergency department after a fall that fractured the femoral neck. At admission, plasma sodium, chloride, and potassium concentrations were all within their respective reference intervals. The plasma concentration of total protein was 5. 4 showed the presence of an unusual spike in the ␤ region (Fig. 1A). We measured an increased urine concentration of free light chain [1.4 mg/dL (14 mg/L); reference interval, 0 -0.2 mg/dL (0 -2 mg/L)], along with a normal concentration of urine ␤ 2 -microglobulin.The patient underwent surgical repair of his left femur. In the meantime, our laboratory asked for serum to complete the investigation of the abnormal UPEP pattern. Investigations of the serum sample revealed a decreased albumin concentration [1.45 g/dL (14.5 g/L); reference interval, 3.0 -4.5 g/dL (30 -45 g/L)]. Immunoglobulin quantification revealed an increased IgG value [2950 mg/dL (29.5 g/L); reference interval, 700 -1000 mg/dL (7-10 g/L)]. IgA and IgM were within their respective reference intervals. Serum protein electrophoresis (SPEP) showed an increased ␣1 region, along with decreased albumin and ␥ regions. Moreover, we found an increased ␤ region (19.1 g/L, quantified from the electrophoresis trace and the total protein concentration), along with a loss of separation between the ␤1 and ␤2 regions because of a narrow spike (Fig. 1B). With a normal concentration of ␤-globulins of approximately 300 mg/dL (3 g/L), we estimated the monoclonal protein concentration at approximately 1600 mg/dL (16 g/L). Serum immunofixation was performed with antibodies specific for heavy chains (G, A, M) and light chains (, ). A band was present in the IgG lane with a ␤ electrophoretic mobility, with no corresponding band for the light chain (Fig. 1C). Serum free light chains included a decreased free chain [0.06 mg/dL (0.6 mg/L); reference interval, 0.33-1.94 mg/dL (3.3-19.4 mg/L)], a decreased free

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“…Les IgG2, quant à elles, peuvent former plusieurs isoformes structurales (A, B, A/B, etc.) caractérisées par des appariements différents de ponts disulfures entre chaînes lourdes et légères [20], ainsi que des dimères covalents [21]. Ces appariements sont sensibles à l'environnement redox in vitro et in vivo (par ex.…”

Section: Alain Beck Elsa Wagner-rousset Thierry Wurch Nathalie Corunclassified