NATURALLY OCCURRING ANTIBODIES TO LIPOSOMES .1. RABBIT ANTIBODIES TO SPHINGOMYELIN-CONTAINING LIPOSOMES BEFORE AND AFTER IMMUNIZATION WITH UNRELATED ANTIGENS

  • 1 January 1979
    • journal article
    • research article
    • Vol. 123  (1) , 370-378
Abstract
Liposomes were prepared from a mixture of sphingomyelin, cholesterol and dicetylphosphate or L-.alpha.-dimyristoyl phosphatidylcholine, cholesterol and dicetylphosphate, in the presence of glucose. The amount of trapped glucose released from these liposomes was monitored after incubation with a variety of normal and immune sera in the presence of guinea pig complement [c]. All normal rabbit sera tested released in the presence of C, detectable amounts of trapped glucose from sphingomyelin-containing liposomes. After immunization with a variety of unrelated antigens, the anti-sphingomyelin liposome activity increased significantly and in direct proportion to the number of injections, despite the fact that the liposomes used in the assay did not contain the relevant antigen used for immunization. Liposomes prepared from dimyristoyl phosphatidylcholine showed only marginal release of their trapped marker when assayed with the same rabbit sera and C. These liposomes were fully reactive when the appropriate antigen was inserted in their bilayer structure. The anti-liposome activity was associated mainly with the Ig[immunoglobulin]M antibody class. Antigenic stimulation may trigger the activation of lymphocyte clones directed against autologous cell-membrane components that cross-react with artificial model membranes containing sphingomyelin.

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