Down-regulation of CD99 in LMP-1 overexpressing IM9 cells.

IM9 B cells were transfected with either vector (Vec-TF), LMP-1 (LMP-1-TF), or antisense-CD99 (AS-TF) expression construct, and G418-resistant stable clones were obtained. (A) Flow cytometric analyses of LMP-1-TF cells. The cells were first stained with control monoclonal antibody or CD99 monoclonal antibody, and then with FITC-conjugated goat anti-mouse IgG antibody. (B) Vec-TF (V) and LMP-1-TF (L) IM9 cells were examined for LMP-1 expression by immunoblot. (C and D) Immunoblot and Northern blot analyses of LMP-1-TF IM9 cells. Expression of CD99 molecules was examined in Vec-TF (V), LMP-1-TF (L), and AS-TF (A) IM9 cells by immunoblot (C) and Northern blot (D) analysis. Calnexin (C) and GAPDH (D) were tested as internal controls. LMP-1-TF cells displayed down-regulation of CD99 expression at the transcriptional level.