EXPRESSION AND FUNCTION OF FC-GAMMA-RII ON HUMAN NATURAL-KILLER-CELLS

In this report, we present data on the expression and function of Fc g amma RII (CD32) by natural killer (NK) cells, Highly enriched NK cell populations were isolated from peripheral blood lymphocytes by negativ e selection and consisted of greater than or equal to 95% CD3-/ CD56cells. Flow cytometric analyses with anti-CD32 monoclonal antibodies ( mAbs) demonstrated that a small proportion of NK cells were recognized by mAbs IV.3 and 41H16. Two-color flaw cytometric analysis indicated coexpression of the epitope on NK cells recognized by both these mAbs, Verification of expression of CD32 on NK cells was obtained by demons trating coexpression of CD32 on either CD16+ or CD56+ cells. The CD32/CD16+ and CD32+/CD56+ cells represented approximately 7 and 3% of the total, respectively. CD32 transcripts were identified from highly pur ified NK cells using reverse transcription-polymerase chain reaction w ith CD32-specific primers, followed by Southern blotting. Enhanced che miluminescence-Western blot (ECL-WB) analysis of lysates of purified N K cells indicated that mAb IV. 3 recognized a molecule of approximatel y 40 kD. The Fc gamma RII on NK cells was able to transduce intracellu lar signals in several types of assay. Cross-linking of anti-CD32 resu lted in a mobilization of intracellular Ca2+, although to a lesser ext ent than that induced by cross-linking CD16. Both mAbs IV.3 and 41H16 were found to be capable of inducing reverse antibody-dependent cellul ar cytotoxicity against FcR+ target cells (e.g. P815), These data repr esent the first direct description of the expression and function of F c gamma RII on human NK cells.