Suppression of Allogeneic Rabbit Lymph Node Cells: Antigen-Bearing Cell Membrane Fragments and the Specifically Purified Suppressive Antibody

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Abstract
Summary: For study of the suppressive antibody in rabbit anti-rabbit-leukocyte serum, a fraction of lymph node cells was sought which could bind this antibody. In preliminary serologic exploration, complement fixation vs. the anti-leukocyte serum was used. On sonic disruption of washed cells, differential centrifugation yielded a fraction—a high-speed sediment of the supernatant of lower speed centrifugation—which had almost all of the complement-fixing activity of the original suspension of whole cells. A far better source of material of the same centrifugal properties and serologic activity was unexpectedly found in the cell wash fluids, where detached cell membrane fragments could be found in 4 to 5 times the yield obtained from disruption of the same cells after washing. The association of the antigenic material in cell membrane fragments with suppression of allogeneic lymph node cells was shown by ability of these fragments to absorb the suppressive antibody from an anti-leukocyte serum, to induce actively, on injection into rabbits, the suppression of antibody synthesis by subsequently transferred lymph node cells, and to stimulate the production of suppressive antibody on injection into normal rabbits. From the specific complexes produced by absorption of the allo-antibodies in anti-leukocyte serum on cell fragments, it was possible to elute the suppressive antibody with recovery of about 25%. The antibody was found to be a water-soluble γ-globulin of 6.6 S.