Cathepsin A is expressed in primary human antigen-presenting cells.
Cathepsins are expressed in antigen-presenting cells (APC). These cathepsins are known to regulate antigen processing and degradation of the invariant chain (Ii) into the class II-associated Ii peptide (CLIP), which occupies the peptide-binding groove of the major histocompatibility complex (MHC) class II molecule. Previous studies have identified the serine carboxypeptidase cathepsin A (CatA) in various tissues and cells; however, it is not clear whether CatA is also expressed in primary human APC. We demonstrate the expression of CatA in B lymphoblastoid cells (BLC), primary human B cells, both subsets of myeloid dendritic cells (mDC1 and mDC2), as well as in plasmacytoid DC. PMSF or lactacystin-mediated inhibition of serine proteases in BLC-derived lysosomal proteases resulted in the inhibition of amino acid release from the C-terminal end of two model peptides. This inhibition did not occur by using a proline rich peptide. Our data suggest that CatA is involved in the C-terminal fine-tuning of antigenic T cell epitopes in human APC.
Reich
Michael
M
Division of Endocrinology and Diabetes, Center for Internal Medicine, University Medical Center Ulm, Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany.
Spindler
Klaus-Dieter
KD
Burret
Michael
M
Kalbacher
Hubert
H
Boehm
Bernhard O
BO
Burster
Timo
T
D000595:Amino Acid Sequence; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000378:metabolism; D000941:Antigens / Q000737:chemistry / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D043402:Cathepsin A / Q000378:metabolism*; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000276:immunology
D000941:Antigens; D010455:Peptides; D043402:Cathepsin A