Capping of HLA antigens in human lymphocytes as followed by immunogold label-fracture.
We used immunogold label-fracture to follow the migration of HLA I class and HLA II class antigens during capping as induced by specific monoclonal antibodies. Capping is achieved through a process of clustering and "consolidation" of clusters into larger patches and, finally, a single cap. All receptors appear to cluster from the very start, with no "stray" molecules joining already formed patches. Characterization of exoplasmic and protoplasmic fracture-faces of capping cells fails to reveal any corresponding accumulation of intramembrane particles and/or subtler rugosities. Our results are consistent with the concepts that view the migration of capping molecules as contemporaneous with the efflux of noncapping integral membrane proteins.
Dipartimento di Medicina Sperimentale, Università di Roma La Sapienza, Italy.
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Pavan
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Mancini
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Cirone
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Frati
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Torrisi
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Pinto da Silva
D000911:Antibodies, Monoclonal / Q000276:immunology; D005614:Freeze Fracturing; D015395:Histocompatibility Antigens Class I / Q000032:analysis / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000032:analysis / Q000276:immunology*; D006801:Humans; D007150:Immunohistochemistry; D007152:Immunologic Capping; D008214:Lymphocytes / Q000276:immunology* / Q000648:ultrastructure; D008854:Microscopy, Electron
D000911:Antibodies, Monoclonal; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II