The Use of Human F(ab′)2 Fragments as Blocking Agents in the Mixed Lymphocyte Reaction

Autor: M. O. Hornung, E. Layne, J. C. McDonald
Rok vydání: 1971
Předmět:
Zdroj: The Journal of Immunology. 107:979-984
ISSN: 1550-6606
0022-1767
DOI: 10.4049/jimmunol.107.4.979
Popis: F(ab′)2 fragments free of contaminating IgG were prepared from purified IgG obtained from two human anti-HL-A sera. One serum was polyspecific, reacting with 80% of a panel of allogeneic cells in cytotoxicity tests; the other was monospecific anti-HL-A1. The F(ab′)2 fragments were non-cytotoxic but did bind to appropriate HL-A type cells as judged by immunofluorescence studies. Test cells, selected from among those that reacted positively in cytotoxic studies with each serum, were incubated with whole serum or F(ab′)2 fragments (15 mg/ml), then washed, irradiated and tested for their ability to stimulate target cells. The latter were selected as non-reactive in the cytotoxicity test but lacking antigens present on the test cells. All cells were O Rh+ and gave a normal response to PHA. In the mixed lymphocyte reaction, test cells treated with cytotoxic serum or F(ab′)2 fragments did not stimulate the target cells, whereas untreated test cells gave significant stimulation. The effect was complete when polyspecific anti-HL-A serum was used but only partial when monospecific anti-HL-A 1 serum was used in a system in which the test cells carried, in addition to HL-A 1, three other foreign HL-A antigens (3, 5, 8). It was suggested that the mechanism of action is alteration of the test cells' membrane potential by aggregated IgG or F(ab′)2, causing them to repel negatively charged lymphocytes and thus fail to establish the contact required for lymphocyte activation. The F(ab′)2 fragments of human cytotoxic anti-HL-A sera appeared to have the necessary qualitative properties required for an immunologically specific immunosuppressive agent in human transplantation.
Databáze: OpenAIRE
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