Expression of caveolin by bovine lymphocytes and antigen-presenting cells.
Caveolin is a generic term for a family of proteins that include caveolin-1, -2 and -3. Although the distribution of these proteins varies between cells, caveolin-1 and -2 are commonly found coating membrane invaginations known as caveolae. Studies on human and murine cells suggest that caveolin/caveolae can be found in neutrophils, macrophages and mast cells, in which they are involved in the uptake of pathogens, but not in lymphocyte cell lines. Expression of caveolin-1, -2 and -3 in bovine immune cells was investigated using confocal microscopy and Western blotting. Staining for caveolin-1 was evident in all peripheral blood mononuclear cells (PBMC) and in CD4+, CD8+ and CD21+ lymphocytes, monocytes, macrophages and monocyte-derived dendritic cells (DC). In addition, the caveolin-1 antibody detected a protein with a molecular weight of approximately 22[?]000 in all PBMC, macrophages and DC, as well as in bovine aortic endothelial (BAE)-1 cells and human endothelial cells by Western blotting. In macrophages and DC, caveolin co-localized with the endoplasmic reticulum--Golgi intermediate compartment (ERGIC) and to a lesser extent with Golgi, but not with endoplasmic reticulum. Staining was not seen on the plasma membrane in any bovine immune cells, suggesting the absence of caveolae, while in BAE-1 cells staining was predominantly on the cell membrane. Caveolin-2 could not be detected in any bovine cells by confocal microscopy or Western blotting, while caveolin-3 was detected in all bovine cells by Western blotting, but not by confocal microscopy. These data provide evidence for the presence of caveolin in bovine lymphocytes and antigen-presenting cells.
Harris
James
J
Division of Immunology and Pathology, Institute for Animal Health, Compton Laboratory, Near Newbury, Berkshire RG20 7NN, UK.
Werling
Dirk
D
Koss
Michael
M
Monaghan
Paul
P
Taylor
Geraldine
G
Howard
Chris J
CJ
D000818:Animals; D000938:Antigen-Presenting Cells / Q000378:metabolism*; D002417:Cattle; D051242:Caveolin 1; D051244:Caveolin 3; D022461:Caveolins / Q000378:metabolism*; D002478:Cells, Cultured; D004721:Endoplasmic Reticulum / Q000276:immunology; D006056:Golgi Apparatus / Q000276:immunology; D008214:Lymphocytes / Q000378:metabolism*; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins / Q000378:metabolism; D018613:Microscopy, Confocal
D051242:Caveolin 1; D051244:Caveolin 3; D022461:Caveolins; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins