NK cells can recognize and lyse target cells without restriction by th
e MHC. The molecular interaction responsible for NK cell recognition i
s poorly understood. It has been frequently suggested that the loss of
beta(2) integrin in immune competent cells may lead to dysfunction du
e to inadequate cell-cell interaction. We examined the role of lymphoc
yte functional adhesion molecule-1 in the function of a human natural
killer leukemia cell line, YT-1. A mutant YT-1(-) cell subclone showed
an absence of killing activity against a B lymphoma cell line, compar
ed with that against a CD11a/CD18 positive parental cell line, YT-1(+)
cells. We found that this loss of cytotoxicity was correlated with la
ck of surface expression of CD11a/CD18 molecules due to the mutation o
f the CD18 gene. Using gene transfer experiments, we provide strong ev
idence demonstrating that CD18 transfection to this mutant NK cell lin
e, YT-1(-), restored the surface expression of CD11a/CD18, and this re
storation was accompanied by reexpression of cytotoxic function. (C) 1
994 Academic Press, Inc.