Effect of a single amino acid mutation on the activating and immunosuppressive properties of a 'humanized' OKT3 monoclonal antibody
| Autor: | M L Alegre, A M Collins, V L Pulito, R A Brosius, W C Olson, R A Zivin, R Knowles, J R Thistlethwaite, L K Jolliffe, J A Bluestone |
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| Rok vydání: | 1992 |
| Předmět: | |
| Zdroj: | The Journal of Immunology. 148:3461-3468 |
| ISSN: | 1550-6606 0022-1767 |
| DOI: | 10.4049/jimmunol.148.11.3461 |
| Popis: | The binding specificity of the murine OKT3 has been transferred into a human antibody framework to reduce its immunogenicity. This "humanized" anti-CD3 mAb (gOKT3-5) was previously shown to retain, in vitro, all the properties of native OKT3, including T cell activation, which has been correlated, in vivo, with the severe side effects observed in transplant recipients after the first administration of the mAb. T cell activation is thought to be triggered by the cross-linking mediated by the antibodies between T cells and Fc receptor-bearing cells. In this study, we introduced a single amino acid mutation from a leucine to a glutamic acid at position 235 in the Fc receptor binding segment of the gOKT3-5 mAb to produce Glu-235 mAb. This mutation generated a 100-fold decrease in the affinity of the antibody for the Fc receptor on U937 cells, without affecting Ag binding. In parallel, we observed a marked reduction in the T cell activation triggered by the mAb (proliferation, cell surface expression of early activation markers including Leu 23 and IL-2R, and release of TNF-alpha, IFN-gamma, and granulocyte macrophage-CSF). In contrast, the mutated mAb retained suppressive properties similar to the gOKT3-5 mAb, as assessed by significant modulation of the T cell receptor complex and suppression of Ag-specific CTL activity. We conclude that this anti-CD3 mAb bearing a single amino acid mutation in its Fc portion retains important immunosuppressive properties, while exhibiting significantly less T cell activation than OKT3 in vitro. This drug might achieve potent immunosuppression while minimizing acute toxicity in vivo and thus be useful in transplantation as well as in autoimmune diseases. |
| Databáze: | OpenAIRE |
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