The present invention relates to anti-CD277 antibodies which: - activates or inhibit the cytolytic function of V³9/V´2 T cells, and/or - costimulates T cells together with CD3-TCR, and/or - costimulates T cells in addition to CD28-B7 costimulation, and/or - increases the activity and/or survival of monocytes and dendritic cells. The invention also relates to the use of said antibodies in therapy.