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.
Pavan
A
A
Dipartimento di Medicina Sperimentale, Università di Roma La Sapienza, Italy.
Mancini
P
P
Cirone
M
M
Frati
L
L
Torrisi
M R
MR
Pinto da Silva
P
P
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