Biochemical and serologic evidence for the existence of functionally distinct forms of the CD94 NK cell receptor.
The CD94 NK cell receptor is assembled as a disulfide-linked dimer and appears to be encoded by a single-copy gene of the C-type lectin superfamily. In reverse Ab-dependent cellular cytotoxicity assays, CD94-specific mAbs may either trigger or inhibit cytotoxicity in distinct subsets of NK clones, termed groups A and B, respectively. The molecular basis for this functional ambivalence of CD94 has been addressed. CD94 molecules immunoprecipitated with the HP-3B1 mAb from the two different subsets of NK clones were comparatively analyzed by SDS-PAGE. Under reducing conditions, the stimulating form of CD94 from group A clones displayed a significantly lower Mr (39 kDa) than the inhibitory form of group B clones (Mr = 43 kDa). Analyses of N-glycanase and V8 protease-digested samples indicated that the two CD94 forms are homologous. A CD94-specific mAb (Z199) that did not recognize cells transfected with a CD94 cDNA (LL288) was characterized. Z199 did not bind to group A clones, whereas its reactivity with group B NK cells was indistinguishable from that of other CD94-specific mAbs. Different from the HP-3B1 mAb, the Z199 mAb displayed only inhibitory effects in reverse Ab-dependent cellular cytotoxicity assays. Immunoprecipitation studies confirmed that Z199 selectively identified the 43-kDa CD94. Our study proves the existence of at least two biochemically and serologically distinct CD94 molecules, whose selective/predominant expression at the clonal level correlates with the pattern of response (i.e., inhibition vs activation) of NK cells to ligation by CD94-specific mAbs.
Pérez-Villar
J J
JJ
Immunology Service, Hospital de la Princesa, Autonomous University of Madrid, Spain.
Carretero
M
M
Navarro
F
F
Melero
I
I
Rodríguez
A
A
Bottino
C
C
Moretta
A
A
López-Botet
M
M
D015703:Antigens, CD / Q000737:chemistry / Q000276:immunology*; D003602:Cytotoxicity, Immunologic; D006801:Humans; D007111:Immunity, Cellular; D007694:Killer Cells, Natural / Q000276:immunology*; D037181:Lectins, C-Type; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000276:immunology*; D008970:Molecular Weight; D051920:NK Cell Lectin-Like Receptor Subfamily D; D010449:Peptide Mapping; D011233:Precipitin Tests; D011971:Receptors, Immunologic / Q000737:chemistry / Q000276:immunology*
D015703:Antigens, CD; C497869:KLRD1 protein, human; D037181:Lectins, C-Type; D008562:Membrane Glycoproteins; D051920:NK Cell Lectin-Like Receptor Subfamily D; D011971:Receptors, Immunologic