Capping of HLA antigens in human lymphocytes as followed by immunogold label-fracture |
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Authors: | A Pavan P Mancini M Cirone L Frati M R Torrisi P Pinto da Silva |
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Institution: | Dipartimento di Medicina Sperimentale, Università di Roma La Sapienza, Italy. |
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Abstract: | 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. |
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