Desensitization <em>in vitro</em>-The Specific Inhibition, by Antigen, of the Passive Transfer of Delayed Hypersensitivity by Peritoneal Exudate Cells.

A preliminary experiment showed that the injection of bovine γ-globulin into guinea-pigs with delayed hypersensitivity to bovine γ-globulin reduced the 24-hour skin reactions to bovine γ-globulin and (to a lesser extent) PPD. The peritoneal exudate cells from the desensitized donors had a reduced ability to transfer delayed hypersensitivity to bovine γ-globulin but a normal ability to transfer delayed hypersensitivity to PPD. Likewise, it was possible to diminish the passive transfer of delayed hypersensitivity to bovine γ-globulin by peritoneal exudate cells, by exposure of the ceils to bovine γ-globulin in vitro. The recipients were tested immediately after cell transfer. This in vitro desensitization was specific, in that the transfer of delayed hypersensitivity to PPD was unaffected. Exposure of cells in vitro to hypotonic conditions and antibody to guinea-pig γ-globulin did not prevent the passive transfer of delayed hypersensitivity. [ABSTRACT FROM AUTHOR]