Identification of a cell-surface antigen selectively expressed on the natural killer cell*

Abstract

We have studied the cell-surface phenotype of natural killer (NK) cells of NZB and B6 mice which react to an MuLV+ lymphoid tumor. (a) NK cells do not express Thyl, Ly2, or Ig surface markers. (b) NK cells express an antigen recognized by C3H anti-CE antiserum (‘anti-Lyl.2 antiserum’). Inasmuch as NK activity of spleen cells from B6 and B6/Lyl.1 congenic strains were both equally sensitive to C3H anti-CE antiserum, the αNK antigen is distinct from Lyl.2. This point was confirmed by the observation that aNK activity was removed by absorption of C3H anti-CE antiserum with spleen cells from either B6 or B6/Lyl.1 congenic strains. Absorption of C3H αCE serum with BALB/c thymocytes and spleen cells (which are Lyl.2+NK−) removed anti-Lyl.2 activity and left anti-NK activity intact. This absorption step could be circumvented by inserting the BALB/c genotype into the recipient immunized to CE cells (i.e., (C3H × BALB/c)F1 αCE spleen cells). This antiserum, provisionally termed ‘anti-NK’, defines a new subclass of lymphocytes which may play a central role in the immunosurveillance against tumors. © American Society for Clinical Pathology.