NATURAL KILLER LYMPHOCYTES IN RAT LIVER SINUSOIDAL BLOOD

B Lukomska, T Ruffa, L Olszewski, A Engeset

Abstract


Blood·borne cells with the characteristics described
for the natural killer (NK) lymphocytes were recovered
from the liver sinusoids in rat. They had
cytotoxic activity against K 562 cells in a 18 h Sl Cr
release assay. target binding rate and large granular
lymphocytes percentage higher than the inflowing
portal blood cells. The cytotoxic effector population
was non-adherent and peroxidase negative, enriched
in cells with Fe- and C36-receptors. Deprivation
of liver of portal or mesenteric blood supply
sign ificantly decreased the liver NK activity not affecting
the level of cytotoxicity in the portal blood.
Splenectomy produced only a moderate decrease of
activity. These findings may indicate that liver sinusoids
is the site of accumulation of blood-born NK
cells or of maturation of the NK·precursors. One
possible mechanism by which natural cytotoxicity
controls tumor growth and spread might be the killing
of circulating tumor cells arrested in the liver
by the blood-born NK-cells.


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