Transfection of HLA-DR-expressing DAP.3 cells with a cDNA clone encoding the glycosyl phosphatidylinositol-linked form of lymphocyte function associated antigen-3: biochemical features and functional consequences.
Structural and functional aspects of the accessory molecule lymphocyte function associated antigen (LFA)-3 (CD58) have been examined following the transfection of DAP.3 and P815 cells with a cDNA clone encoding the glycosyl phosphatidylinositol (GPI)-linked form of human LFA-3. Despite earlier observations that DAP.3 cells are deficient in GPI anchoring LFA-3 was expressed efficiently on DAP.3, as well as on P815 cells. Immunoprecipitation of LFA-3 from 35S-labelled cells revealed that the molecule expressed on the DAP.3 cells had a molecular weight intermediate between the transmembrane and GPI-linked forms expressed by human B cells. This suggests that the DAP.3 cells have a default pathway whereby the RNA transcript which encodes the GPI-linked form of the molecule can also encode an integral membrane protein. Functionally, expression of LFA-3 by DAP.3 which had previously been transfected with the genes encoding HLA-DR1 led to a marked augmentation of the proliferative response of five out of eight anti-DR1 human T cell clones. This effect was not reproduced when DR1 and LFA-3 were expressed by separate populations of DAP.3 cells, suggesting that the ligands for CD2 and for the T cell's receptor must be expressed on the same cell membrane. Expression of human LFA-3 also led to a substantial increase in the proliferative response of human peripheral blood T cells to a DR alloantigen. Separation of T cells into CD45RO+ and CD45RO- populations revealed that the augmentation was more marked for the memory than the virgin population. The mechanisms responsible for these differences are discussed.
Greenlaw
R
R
Royal Postgraduate Medical School, Hammersmith Hospital, London, UK.
Robinson
P
P
Heaton
T
T
Lombardi
G
G
Lechler
R
R
D000818:Animals; D015703:Antigens, CD / Q000032:analysis; D000945:Antigens, Differentiation, T-Lymphocyte / Q000502:physiology; D000954:Antigens, Surface / Q000032:analysis / Q000235:genetics* / Q000502:physiology; D018801:CD2 Antigens; D018968:CD58 Antigens; D006017:Glycolipids / Q000502:physiology*; D017261:Glycosylphosphatidylinositols; D006684:HLA-DR Antigens / Q000032:analysis*; D006649:Histocompatibility Antigens / Q000032:analysis; D006801:Humans; D007519:Isoantigens / Q000032:analysis; D017493:Leukocyte Common Antigens; D008562:Membrane Glycoproteins / Q000032:analysis / Q000235:genetics* / Q000502:physiology; D051379:Mice; D010716:Phosphatidylinositols / Q000502:physiology*; D011971:Receptors, Immunologic / Q000502:physiology; D013601:T-Lymphocytes / Q000276:immunology; D014162:Transfection
D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D018801:CD2 Antigens; D018968:CD58 Antigens; D006017:Glycolipids; D017261:Glycosylphosphatidylinositols; D006684:HLA-DR Antigens; D006649:Histocompatibility Antigens; D007519:Isoantigens; D008562:Membrane Glycoproteins; D010716:Phosphatidylinositols; D011971:Receptors, Immunologic; D017493:Leukocyte Common Antigens