C3d and Epstein-Barr virus (CR2/CD21 ligands) stimulate cells of an HTLV-I line, MT-2.
We studied the physiological role of complement receptor type II (CR2, C3d/EBV receptor) expressed on T cells using MT-2 cells. First, we confirmed CR2 expression on MT-2 cells by flow cytometry and found that the MW of CR2 molecules on these cells and Raji B cells were the same by SDS-PAGE analysis. When MT-2 lysates were incubated with anti-CR2 mAb HB5 and thereafter with 32P-labeled ATP, 52- and 74-kDa proteins were phosphorylated, suggesting the activation of MT-2 cells through the complex of CR2 with these proteins. In this respect, we measured lymphotoxin production by MT-2 cells when incubated with C3d or EBV. The cytotoxicity of the MT-2 supernatant against L929 cells was elevated in a dose- and time-dependent manner. Next, we confirmed EBNA expression on EBV-infected MT-2 cells and attempted to establish an EBV-positive MT-2 clone by in vitro EBV infection. However, these clones disappeared during cloning. To clarify this mechanism, we examined the EBV genome in MT-2 cells. By Southern blot analysis, BamHI digestion of DNA extracts from MT-2 cells 3 days after EBV treatment gave a 3.0-kb signal which comigrated with the EBV BamHI-W probe. The 3.0-kb signal of genomic EBV-DNA was detected at 1, 2, 3, 5, and 7 days after EBV treatment, but could not be detected at 14 days. Thus, natural ligands of CR2 stimulate CR2-positive MT-2 cells through their functionally active CR2 molecules and in vitro EBV infection of MT-2 cells might be transient.
Kuraya
M
M
Department of Biochemistry, Fukushima Medical College, Japan.
Sato
T
T
Fujita
T
T
D000818:Animals; D000956:Antigens, Viral / Q000096:biosynthesis; D002460:Cell Line; D003602:Cytotoxicity, Immunologic; D004268:DNA-Binding Proteins / Q000096:biosynthesis; D004591:Electrophoresis, Polyacrylamide Gel; D019309:Epstein-Barr Virus Nuclear Antigens; D005347:Fibroblasts / Q000382:microbiology; D005434:Flow Cytometry; D004854:Herpesvirus 4, Human / Q000254:growth & development / Q000502:physiology*; D015368:Human T-lymphotropic virus 1 / Q000502:physiology*; D008024:Ligands; D008233:Lymphotoxin-alpha / Q000096:biosynthesis; D051379:Mice; D010766:Phosphorylation; D017464:Receptors, Complement 3d / Q000502:physiology*; D013601:T-Lymphocytes / Q000382:microbiology / Q000502:physiology*; D014407:Tumor Cells, Cultured
D000956:Antigens, Viral; D004268:DNA-Binding Proteins; D019309:Epstein-Barr Virus Nuclear Antigens; D008024:Ligands; D008233:Lymphotoxin-alpha; D017464:Receptors, Complement 3d