Binding of HLA antigen-containing liposomes to bacteria

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Abstract
Highly purified, detergent-solubilized HLA-A and -B antigens and HLA-D antigens were separately incorporated into liposomes. Detergent-solubilized transplantation antigens, but not papain-solubilized antigens lacking the membrane-integrated portions of the molecules, were bound to the liposomes. A considerable portion of the liposome-bound antigens displayed accessible antigenic sites, suggesting that they were oriented in the right-side-out direction. Liposomes containing the HLA-A and -B antigens or the HLA-D antigen interacted similarly with bacteria. The 2 types of liposomes bound efficiently to 2 strains of Neisseria [Branhamella] catarrhalis and to 1 strain of Haemophilus influenzae, weakly to 1 strain of Escherichia coli and not at all to another strain of E. coli. The binding between the HLA antigen-containing liposomes and 1 strain of N. catarrhalis was abolished when Fab fragments directed against the H chains of HLA-A and -B antigens or against HLA-D antigens, respectively, were added. Fab fragments against .beta.2-microglobulin did not measurably impede the bacteria-liposome interaction suggesting that, with regard to the HLA-A and -B antigens, the H, but not the L, chains interacted with the bacteria. N. catarrhalis preferentially interacted with transplantation antigens when mixed with detergent-solubilized lymphocyte membrane glycoproteins. HLA-A and -B and HLA-D antigens may have the function of interacting with foreign antigens such as bacteria.