Transfer of antigen-presenting capacity to Ia-negative cells upon fusion with Ia-bearing liposomes.
The role of Ia in T cell activation was investigated by incorporating affinity-purified I-Ad molecules into synthetic liposomal membranes and by using these as antigen-presenting units. IL 2 production by I-Ad-restricted, chicken ovalbumin-specific T cell hybridomas was measured in a system in which antigen processing by the presenter was not required. I-Ad-bearing liposomes were found to have no antigen-presenting capacity. It was shown, however, that antigen-presenting capacity could be conferred on Ia-negative cells by fusion of these cells with liposomes bearing I-Ad molecules, together with Sendai virus envelope glycoproteins, as fusogenic agents. Both Ia-negative B lymphoma cells and mouse L cells were capable of antigen presentation of predigested ovalbumin after fusion with vesicles formed from phosphatidylserine and phosphatidylethanolamine in a 1:1 w:w ratio. The cell surface expression of the transferred Ia remained stable for at least 7 hr. These results indicate that Ia is the only additional cell surface molecule required, at least by Ia-negative B cell lymphomas and L cells, to convert them into effective antigen-presenting cells. This system should be useful in future studies of the cellular requirements for antigen processing and presentation.
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D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology* / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D000949:Histocompatibility Antigens Class II / Q000276:immunology* / Q000302:isolation & purification; D006825:Hybridomas / Q000276:immunology; D008081:Liposomes / Q000276:immunology* / Q000378:metabolism; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D010222:Parainfluenza Virus 1, Human; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D014759:Viral Envelope Proteins / Q000378:metabolism*; D014760:Viral Fusion Proteins
D000949:Histocompatibility Antigens Class II; D008081:Liposomes; D014759:Viral Envelope Proteins; D014760:Viral Fusion Proteins