An Experimental and Clinical Study of Influence of Obstructive Jaundice on Human Natural Killer Activity

yoshiro Iga

First Department of Surgery, Niigata University School of Medicine (Director: Prof. Terukazu Muto)

The present study was designed to evaluate the influence of obstructive jaundice on human natural killer (NK) cell activity and to elucidate the mechanism whereby this influence is exerted. In 7 clinical cases of jaundice the serum levels of 4 bile acids, i.e., glycocholic acid (GCA), taurocholic acid (TAC), glycochenodeoxycholic acid (GDCA) and taurochenodeoxycholic acid (TCDCA), were markedly elevated. NK activity in patients with obstructive jaundice (12.2±2.8%) was lower than normal (43.9±6.7%), but it returned to normal after biliary drainage. Seven-day incubation of lymphocytes from normal volunteers with sera from 6 patients with jaundice resulted invariably in strongly suppressed NK activity in vitro (4.9±5.6%). In a similar experiment, NK activity was entirely unaffected by 7-day incubation with conjugated bilirubin, TCA, TCDCA and GCA, whereas it was significantly inhibited by over 5-day incubation with GCDCA (5-day; 5.6±2.6%, 7-day; 4.3±3.5%, p<0.01). These data clearly indicate that sera from patients with obstructive jaundice suppress NK activity, suggesting that GCDCA is one of the important factors inhibiting NK activity.

Key words
inhibition of natural killer activity, obstructive jaundice, glycochenodeoxycholic acid

Reprint requests
Yoshiro Iga First Department of Surgery, Niigata University School of Medicine
1-757 Asahimachi-dori, Niigata, 951 JAPAN

Accepted
December 10, 1991

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