Effect of anti-CD2 mAbs on bovine NK cell functions. (A) IFN-γ response from NK cells caused by cross-linking of CD2. Plastic wells were pre-coated with two different mAbs against bovine CD2, along with NKp46-mAb as positive control and CD8-mAb or medium as negative controls. rbIL-2 activated NK cells were added and incubated for 24 h in the presence or absence of rbIL-12 (0.5 U/ml), and IFN-γ content in the supernatants analyzed by an ELISA. Data shown are means ± SD of two to four individual animals. (B-C) IL-2 activated NK cell killing of the bovine target lines BL3.1 and MDBK in a 4 h 51Cr-release assay, with addition of the indicated mAbs for blocking. CD2mAb I = BAQ95A, CD2 mAb II = MUC2A, CD8 mAb = CACT80C, NKp46 mAb = AKS1. (D) As above, using murine Fc-receptor bearing P815 target cells to obtain a redirected lysis effect. Data shown in (B-D) are from one animal representative of three to five.