CD1 expression is not affected by human peptide transporter deficiency.
Conventional major histocompatibility complex class I molecules are highly polymorphic and present peptides to cytotoxic T cells. These peptides derive from the proteolytic degradation of endogenous proteins in the cytosol and are translocated into the endoplasmic reticulum by a peptide transporter consisting of two transporter associated with antigen processing (TAP) molecules. Absence of this transporter leads to the synthesis of unstable peptide free class I molecules that are weakly expressed on the cell surface. Mouse nonconventional class I molecules (class Ib) may also present TAP-dependent peptides. In humans, CD1 antigens are nonconventional class I molecules. Recently, we characterized a human HLA class I deficiency resulting from a homozygous TAP deficiency. We show here that CD1a and -c are normally expressed on epidermal Langerhans cells of the TAP-deficient patients, as are CD1a, -b, and -c on dendritic cells differentiated in vitro from monocytes. Moreover, the CD1a antigens present on the surface of the dendritic cells are functional, since they internalize by receptor-mediated endocytosis gold-labeled F(ab')2 fragments of an anti-CD1a mAb. This suggests either that CD1 molecules are empty molecules, that they are more stable than empty conventional class I proteins, or that CD1 molecules present TAP-independent peptides.
Hanau
D
D
Histocompatibility Laboratory, Regional Center for Blood Transfusion, Strasbourg, France.
Fricker
D
D
Bieber
T
T
Esposito-Farese
M E
ME
Bausinger
H
H
Cazenave
J P
JP
Donato
L
L
Tongio
M M
MM
de la Salle
H
H
D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000502:physiology*; D000293:Adolescent; D017951:Antigen Presentation / Q000276:immunology; D015703:Antigens, CD / Q000096:biosynthesis*; D018949:Antigens, CD1; D002478:Cells, Cultured; D005260:Female; D005434:Flow Cytometry; D006680:HLA Antigens / Q000502:physiology; D015395:Histocompatibility Antigens Class I / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D009000:Monocytes / Q000166:cytology / Q000648:ultrastructure
D000071450:ATP Binding Cassette Transporter, Subfamily B, Member 3; D018528:ATP-Binding Cassette Transporters; D015703:Antigens, CD; D018949:Antigens, CD1; D006680:HLA Antigens; D015395:Histocompatibility Antigens Class I; C489516:Tap2 protein, mouse; C071692:TAP2 protein, human