Abstract
In order to study the mechanisms involved in the decreased LAK activity in HCC patients, factors involved in LAK activity induction were investigated on peripheral blood mononuclear cells (PMNC) of HCC patients with normal and low LAK activity and healthy volunteers.
1) In the experiments using PMNC of healthy volunteers and HCC patients with normal LAK activity, the addition of anti-γ-interferon (γ-IFN) to the LAK induction system at the start of incubation resulted in the suppression of LAK activity. In HCC patients with low LAK activity, γ-IFN production in LAK activity induction was significantly lower than that in healthy volunteers, HCC patients with normal LAK activity and liver cirrhosis patients. The addition of recombinant γ-IFN (r-γIFN) to the LAK induction system in HCC patients with low LAK activity enhanced the decrease in LAK activity.
From these results, it was suggested that γ-IFN played an important role in the induction of LAK activity.
2) PMNC subpopulations of HCC patients with low LAK activity were not significantly different from those of healthy volunteers. In healthy volunteers and HCC patients with normal LAK activity, LAK activities and γ-IFN concentrations in culture supernatants were decreased by the deletion of the Leu 7 positive or the Leu 11 positive cell populations, however the level of decreased LAK activities were still higher than that of HCC patients with low LAK activity. These were not enhanced significantly by the addition or r-γIFN.
In conclusion, it was suggested that the decrease in LAK activity in HCC patients was due to not only the impaired γ-IFN production but also the abnormalities of various LAK precursor cells.
