Liver resection for hepatic metastasis from colorectal carcinoma

One hundred and eighteen patients who suffered from metastatic liver tumors from colorectal carcinoma during the period from January 1980 to June 1991 at the National Taiwan University Hospital were retrospectively reviewed. The modes of treatment included hepatic resection (n = 18), transarterial embolization (TAE, n = 17), chemotherapy only (C/T, n = 36), and no treatment (n = 47). In the 18 patients who underwent hepatic resection during the last 10 years, the types of surgery included: wedge resection (n = 8), segmentectomy (n = 2), right hepatic lobectomy (n = 5), left hepatic lobectomy (n = 2) and extended right hepatic lobectomy (n = 1). There were no operative mortalities in this series. The overall three-year actuarial survival rate of the resection group was 57.5%. It was better than that of the TAG group (17%, p < 0.05). For a solitary tumor, the three-year actuarial survival rate rose to 64% in the resection group. There were no three-year survivors in the nonsurgical solitary tumor group. This experience defends aggressive surgical treatment of resectable hepatic metastatic liver cancer from colorectal carcinoma as a safe procedure which is able to prolong a patient's life.

Nucleotide sequence of a full-length cDNA encoding a common precursor of platelet aggregation inhibitor and hemorrhagic protein from Calloselasma rhodostoma venom

The nucleotide sequence of a full-length cDNA encoding the common precursor of a platelet aggregation inhibitor, rhodostomin and a hemorrhagic protein from Calloselasma rhodostoma snake venom is presented. The 1.98-kb cDNA contains an open reading frame encoding 478 amino acid residues. The complete structure of the precursor protein encoded by the cDNA is elucidated.

Microinjection of Rap2B protein or RNA induces rearrangement of pigment granules in Xenopus oocytes

Rap2B, a member of the ras superfamily of low-molecular-mass GTP-binding proteins, induced a characteristic rearrangement of the pigment granules in Xenopus oocytes following its microinjection, resulting in numerous unpigmented spots on the animal hemisphere. This phenomenon, termed 'mottling', was also induced by microinjection of in vitro-transcribed Rap2B RNA or of purified recombinant Rap2A. Following the microinjection of Rap2B, more than 90% of the oocytes showed signs of mottling within 10 h. The time course of mottling paralleled the association of the recombinant Rap2B with an oocyte membrane fraction. Like other members of the ras superfamily, Rap2B possesses a C-terminal CAAX motif that serves as a signal for post-translational processing. Mutation of the cysteine residue in the CAAX motif to serine prevents the association of Rap2B with oocyte membranes, and also prevents mottling. This result suggests that post-translational processing of Rap2B is required for the observed effect. Mottling was blocked by boiling Rap2B prior to its microinjection or by co-injection of the cytoskeletal reagent phalloidin.

Comparison of DNA stemline and cell kinetics between primary breast cancer and its lymph node metastasis

Quantitative measurement of nuclear DNA in individual cells was performed on imprint smears of surgical specimens from 25 primary breast cancers and their concurrent regional lymph node metastases (LNMs). Twenty-five paired imprints taken from primary tumors and their LNMs were stained with the modified Feulgen method. The DNA content was measured with a scanning microdensitometer at a wavelength of 550 nm. The status of estrogen receptors in the primary tumor was measured with the charcoal-dextran-coated method. The DNA modal values were identical in 22 (88%) of 25 paired imprints. Among 13 estrogen receptor-positive (ER[+]) tumors, the DNA modal values were diploid or near-diploid (< 2.5C) in 8 (62%) primary tumors and 7 LNMs. In 10 estrogen receptor-negative (ER[-]) tumors, only 1 (10%) LNM had a near-diploid DNA modal value; all others were aneuploid. In primary tumors the DNA modal values of ER(+) tumors were significantly different from those of ER(-) tumors. The S-phase fraction value of a primary tumor correlated significantly with that of its LNMs. The percentage of cells with DNA content > 6.0C correlated highly between the primary tumor and its LNM. Of primary tumors, ER(-) tumors had more cells with high DNA content (> 6.0C) than ER(+) tumors did. A great similarity in cumulative DNA histograms between primary tumors and their LNMs was found, irrespective of the status of estrogen receptors. In conclusion, the primary breast cancer and its LNM had similar DNA distribution patterns--e.g., DNA modal value, S-phase fraction value and percentage of cells with high DNA content.(ABSTRACT TRUNCATED AT 250 WORDS)

Circulating intercellular adhesion molecule-1 and lymphocyte subsets involved in immune response of breast cancer

To understand the immune responses of patients with breast cancer, circulating intercellular adhesion molecules-1 (ICAM-1) and lymphocyte subsets were measured in patients with breast cancer and in healthy persons. There were 10 patients of with metastasis, 11 patients breast cancer without metastasis and 9 age-and-sex matched healthy persons. Their serum samples were counted for circulating ICAM-1 levels, and blood cells were calculated for lymphocyte subpopulation including CD3, CD4, CD8 and CD19 by using flow cytometry. Higher levels of circulating ICAM-1 were noted in patients with breast cancer and metastasis than those without metastasis (p < 0.01). Lower percentage of CD8 lymphocyte subset were found ih patients with breast cancer and metastasis than those without metastasis (p < 0.05). Shedding of ICAM-1 antigens from the tumor may block the attachment of cytotoxic T cells, and decreased numbers of cytotoxic T cells may be unable to inhibit the spread of cancer cells. Immune responses of patients with breast cancer may be different between metastatic status and limited status. Further investigations should correlate the results of tissue stains of breast cancer with ICAM-1 and lymphocyte markers with those from peripheral blood.

[Seroepidemiological investigation on Japanese encephalitis in Taiwan (January 1989-December 1991)]

The hemagglutination inhibition (HI) test was used to detect sero-confirmed cases of clinically suspected Japanese encephalitis. The results revealed a total of 76 sero-confirmed cases; 24, 27 and 25 cases respectively for the year 1989, 1990 and 1991. The percentages of sero-confirmed cases with respect to reported cases were 12.97%, 12.33%, 10.04% respectively. The mean percentage was 11.64%. The mean number of sero-confirmed cases in recent three years was 25, and morbidity rate per 100,000 population was 0.125. The number of sero-confirmed cases in 1970 was 269, and morbidity rate per 100,000 was 1.86. The comparison of these two groups showed the ratio of 1:11 and 1:15. It demonstrated that the period of 50% sero-conversion of HI antibody positive pigs appeared two months earlier in the middle of May currently as against the middle of July during the years 1966-1968. The period of JE prevalence likewise shifted two months earlier to the months of May, June and July, with a peak in June in 1989-1991 as against the months of July, August and September with a peak in August in 1966-1968. There occurred a few sporadic cases in other months away from the period of major epidemic. With regard to the geographical distribution of the sero-confirmed cases in recent three years, most JE cases were detected in the Taipei basin and the Kaohsiung-Pingtung river basin. The next numerous cases were found in the terrace which extends from Taoyuan, Hsinchu and Miaoli to the central Taiwan and in the Chiayi-Tainan plain. Only four cases were reported from Ilan, Hualien and Taitung counties. During the years between 1955 and 1967, the vast majority of cases occurred among children, especially of 2-9 years of age. The next suffered group was the age group of 10-14 years. In the meanwhile, the current major group of victim was the age group of 10-14 years and its morbidity rate per 100,000 population was 0.30. The second suffered group was the age group of 20-24 years and its morbidity rate was 0.28, and the third was the age group of 0-9 years and its morbidity rate was 0.16. The percentages of sero-confirmed cases of the above each age group with respect to all sero-confirmed cases were 23.68%, 21.05%, 22.36% respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Identification of beta-subunit of GTP-binding regulatory protein in mitotic spindle

BACKGROUND

The heterotrimeric GTP-binding regulatory protein (G protein) is important in membrane signal transduction. Since the function of the beta-subunit of G protein (G beta) in tumor cells is not well-documented, identification of G beta in tumor cells was performed.

EXPERIMENTAL DESIGN

Immunolocalization, Western blotting, and immunoprecipitation of G beta in mammalian tumor and normal cells were investigated using rabbit antisera against amino and carboxyl terminal peptide fragments of G beta. A human nasopharyngeal carcinoma cell line (NPC-TW039) was used as the cell model because of its short doubling time.

RESULTS

Anti-G beta immunoreactivity was found to be associated with the plasma membrane and the mitotic spindle throughout the mitotic phase of cell replication. Colcemid pretreatment resulted in random distribution of the anti-G beta reaction product in the mitotic cells. The same phenomenon was also seen in various other tumor and normal cell lines. When solubilized membranous, cytosolic, and mitotic spindle fractions were analyzed by Western blotting, G beta (35 +/- 1 kDa) was found to be associated with the plasma membrane and mitotic spindle fractions. Immunoprecipitation of isolated mitotic spindles with anti-G beta further confirmed these results.

CONCLUSIONS

These findings indicate that G beta is closely associated with the mitotic spindle as well as the plasma membrane and may be important in regulation of cell mitosis in addition to transmembrane signal transduction.

Angiodysplasia as a source of intestinal bleeding: report of seven cases

From October 1978 to April 1991, seven patients presenting at the National Taiwan University Hospital with gastrointestinal tract hemorrhage were diagnosed by colonofibroscopy or angiography as having angiodysplasia of the colon and small intestine. There were two men and five women; their ages ranged from 23 to 65 years, with a mean age of 50.3 years. None of these patients were diagnosed by barium enema. Only two patients were diagnosed by colonofibroscopy, and six patients were diagnosed by angiography. Therefore, angiography was the most effective method for diagnosing angiodysplasia. A vascular tuft was the most frequent finding. Six patients with lesions on the right side of the colon underwent a right hemicolectomy, one patient with a lesion on the jejunum underwent a right hemicolectomy initially with segmental resection of the jejunum later. The postoperative courses were smooth, and there has been no further evidence of gastrointestinal blood loss or anemia in the follow-up period. A right hemicolectomy is the treatment of choice because these lesions are frequently multiple; the lesions are found primarily on the right side of the colon.

Intrathecal pertussis toxin treatment attenuates opioid antinociception and reduces high-affinity state of opioid receptors

The effect of pertussis toxin on opioid antinociception was studied in rats. Intrathecal injection of a single dose of pertussis toxin reduced the antinociceptive effect of PL017, a highly selective mu-opioid agonist, in a dose- and time-dependent manner. The maximal effective dose of pertussis toxin was 1 microgram, and the maximal effect was seen at day 3. The effect of the toxin lasted for 2 weeks, and the antinociceptive response recovered partially at the third week. The dose-response curves of the antinociceptive effect of PL017 were shifted to the right with increasing doses of pertussis toxin. Three days after pertussis injection, receptor-binding activity of membranes in the lumbosacral segment of spinal cords decreased to 70% of control as assayed by 125I-FK33824, a highly selective mu-receptor agonist. In experiments using [3H]naloxone as the radiolabeled ligand, displacement curves of FK33824 were shifted to the right after pertussis toxin treatment. The shift also was dose and time dependent. Scatchard analysis of binding data showed that, after pertussis toxin treatment, there was no significant change in the total number of binding sites, but a class of low-affinity binding sites appeared in addition to the high-affinity sites. When spinal membranes were washed in Na+ (100 mM) and guanosine diphosphate (100 microM) and binding was assayed in the presence of Mg2+ (5 mM), all the mu-receptors were in the high-affinity state in control membranes. After the pertussis toxin treatment, the ratio of low-affinity sites to high-affinity sites increased.(ABSTRACT TRUNCATED AT 250 WORDS)

The purification of nucleoside diphosphate kinase from rat brain

Nucleoside diphosphate kinase from the cytosol of rat brain was purified to electrophoretic homogeneity through a series of chromatography columns, including DE-52, AcA-34 Ultrogel, phenyl-Sepharose and Q-Sepharose. The molecular weight of the enzyme was 64,000 as estimated by gel filtration, and it consisted of 3 identical 19,000 subunits. [35S]-GTP gamma S binding and autophosphorylation of the enzyme, and inhibition of the GTPase activity of G-protein were used to screen for the enzyme. These methods were shown to be useful for purifying and assaying the enzyme.

The antibiotic azatyrosine suppresses progesterone or [Val12]p21 Ha-ras/insulin-like growth factor I-induced germinal vesicle breakdown and tyrosine phosphorylation of Xenopus mitogen-activated protein kinase in oocytes

The antibiotic azatyrosine [DL-3-(5-hydroxy-2-pyridyl)alanine] suppressed meiotic maturation in oocytes induced by progesterone or the combination of [Val12]p21Ha-ras microinjection and insulin-like growth factor I. The suppression was dose-dependent in the range of 20-250 microM azatyrosine. In addition, azatyrosine blocked the tyrosine phosphorylation of Xp42, a member of the mitogen-activated protein kinase family, after progesterone or [Val12]p21Ha-ras/insulin-like growth factor I stimulation. Activation of maturation-promoting factor, as shown by a decrease in the tyrosine phosphorylation of the Xenopus homolog of p34cdc2, was also suppressed by azatyrosine. Azatyrosine had no effect in vivo or in vitro on the growth factor-induced autophosphorylation of the oocyte insulin-like growth factor I receptor. Azatyrosine has been shown by others [Shindo-Okada, N., Makabe, O., Nagahara, H. & Nishimura, S. (1989) Mol. Carcinog. 2, 159-167] to inhibit the growth of ras-transformed cells without affecting that of nontransformed cells. In oocytes, the antibiotic exerts an inhibitory action on both a ras-dependent and a ras-independent pathway. Lack of an effect of azatyrosine on germinal vesicle breakdown induced by the microinjection of an extract from mature oocytes, however, suggests that azatryosine is acting upstream of maturation-promoting factor activation.

Induction of ovulation and oocyte maturation of amphibian (Rana dybowskii) ovarian follicles by protein kinase C activation in vitro

We previously reported that protein kinase C (PKC) activation induced meiotic maturation (germinal vesicle breakdown, GVBD) of Rana dybowskii follicular oocytes cultured in vitro without hormone treatment. The experiments reported here were carried out to establish whether ovarian follicles ovulated in response to PKC activation during culture. A phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), was used for PKC activation. TPA addition (10 microM) to cultured ovarian fragments induced ovulation and maturation of the oocytes similar to that seen following addition of frog pituitary homogenate (FPH, 0.05 pituitary/ml) or progesterone (0.5 microgram/ml). Such changes were not observed when ovarian fragments were treated with inactive phorbol ester. The time course of TPA-induced ovulation was similar to that produced by FPH-stimulated ovulation. Both TPA- and FPH-stimulated ovulation and maturation were blocked by treatment with cycloheximide, forskolin (an adenylate cyclase stimulator), and 1-(5-isoquinolinylsulfonyl)-2-methyl-piperazine (H-7; a PKC inactivator). FPH treatment markedly increased progesterone levels in the medium during ovarian fragment culture whereas TPA treatment failed to elevate progesterone levels. Thus, TPA treatment mimics FPH and progesterone in inducing ovulation and meiotic maturation in cultured amphibian ovarian fragments. The data strongly suggest that PKC plays an important role in regulating ovulation as well as in modulating amphibian oocyte maturation during follicular differentiation.

Surgery in cholangitis: bacteriology and choice of antibiotic

Owing the frequent occurrence of intrahepatic stones in orientals, cholangitis presents a real problem. Surgery and antimicrobial drug therapy are the main forms of treatment. A retrospective study of choledochotomy, including biliary tract surgery, performed between July 1987 and June 1990, was conducted. Cases with negative common duct exploration during cholecystectomy were excluded. Among 186 cases, 128 (68%) had positive bile growth, which was defined as cholangitis. Sepsis-related complications occurred in 51 patients (27.4%), including 3 surgical deaths, 30 wound infections, and 18 others. The complication rate was higher in the cholangitis group than in the negative group (37.5% vs. 5.2%). However, if peri-operative antibiotics were effective against the cultured bacteria species, the complication rate was 16.9%; if not, the complication rate was 85.3%. For the different-generation cephalosporins used in the peri-operative period, the complication rates were 32.2%, 20.8%, and 27.6% each for 1st, 2nd, and 3rd generation cephalosporins, with no statistically significant differences. In microbiological study, polymicrobial infection was the rule. On average, 2.3 species were grown from each specimen. Enterococcus proved the most important species with a 54% culture rate. E. coli and Pseudomonas were important gram-negative bacilli, with culture rates of 46.1% and 39.1%, respectively. Anaerobic species were cultured in 12.3% of the patients. For good coverage of cholangitis prior to operation, the proper antibiotic should have potency against gram-positive Enterococcus, gram-negative bacilli, especially Pseudomonas and E. coli, and anaerobic species, especially Bacteroides.

Continuous intrathecal opioid treatment abolishes the regulatory effects of magnesium and guanine nucleotides on mu opioid receptor binding in rat spinal membranes

The regulatory effects of cations and guanine nucleotides on mu receptor binding after opioid drug and pertussis toxin treatment were studied in the rat spinal cord model. Continuous intrathecal (i.t.) infusion with PL017 for 5 days induced tolerance in a dose-dependent manner. Maximal tolerance was observed at day 2. A single i.t. dose (1 microgram) of pertussis toxin also induced tolerance to opioid. When mu receptor binding of the high-affinity sites was determined by 125I-FK33824, spinal membrane preparations from morphine- and pertussis toxin-induced tolerant animals demonstrated approximately 30% less binding than control membranes. Analysis of equilibrium competition binding of FK33824 against [3H]naloxone under a variety of experimental conditions (i.e., cations and guanine nucleotides) revealed differences among control and treated membranes. With Na+ (100 mM) + GDP (100 microM) pretreated membranes and binding assays conducted in the presence of Mg++, all mu receptors were observed to be in a high-affinity state in control membranes, whereas about 30% of receptors were in the low-affinity state in membranes from opioid- and pertussis toxin-treated animals. The increase in the proportion of low-affinity sites was dependent upon the infusion dose of PL017, and the increase correlated well with the degree of opioid tolerance developed. The regulatory effect of 5'-guanylylimidodiphosphate on opioid agonist binding was reduced in membranes from pertussis toxin- or opioid-treated animals. In binding assays conducted in the presence of Na+ (100 mM) + Mg++ (5 mM) + 5'-guanylylimidodiphosphate (30 microM) or Na+ (100 mM) + GDP (100 microM), all mu receptors in control membranes were in a low affinity-state, while those from opioid- or pertussis toxin-treated animals existed in both the high- and the low-affinity states. Continuous i.t. infusion with PL017 at the high dose of 1 microgram/hr for 5 days also decreased significantly (about 40%) the total number of receptors. These studies indicate that continuous opioid infusion and pertussis toxin treatment results in impairment in the receptor-G-protein coupling. This is reflected by the decreased regulatory effects of Mg++ and guanine nucleotides. Thus, in addition to receptor down-regulation, which is induced by PL017 at high doses, receptor-G-protein uncoupling may play a role in opioid tolerance induced by continuous infusion with morphine and PL017.

Inhibition of phosphatidylinositol 4-phosphate kinase by heparin. A possible mechanism for the antiproliferative effects of heparin

Heparin and related glycosaminoglycans are important modulators of vascular smooth muscle cell growth, and may be involved in pathological processes such as atherosclerosis. Since polyphosphoinositide metabolism is a major mechanism for regulating cellular activities, including proliferation, the effects of glycosaminoglycans and polyanionic compounds on the activities of phosphoinositide kinases were characterized. Heparin and heparan sulphate caused dose-dependent inhibitions of rat brain cytosolic phosphatidylinositol 4-phosphate (PIP) kinase activity, with half-maximal inhibitory concentrations of approx. 0.5 and 5 microM respectively. PIP kinase was also inhibited by several dextran sulphates, but was not sensitive to inhibition by keratin sulphate, chondroitin sulphate or hyaluronic acid. Polynucleotides and acidic polypeptides were only weakly inhibitory. Heparin did not alter either the PIP- or the Mg(2+)-dependence of PIP kinase. Addition of heparin to brain membranes suppressed PIP kinase activity without affecting phosphatidylinositol (PI) kinase activity. Heparin interfered with the ability of a GTP analogue to stimulate PIP kinase activity in these membranes, suggesting that it uncouples the kinase from an activating guanine-nucleotide-binding protein. In cultured A-10 vascular smooth muscle cells, heparin caused dose- and time-dependent inhibition of [3H]thymidine incorporation into DNA. Similar treatments with heparin decreased cellular levels of phosphatidylinositol 4,5-bisphosphate (PIP2) without changing PI and PIP levels. Therefore heparin-mediated inhibition of PIP kinase appears to lead to decreases in PIP2 levels which may attenuate cellular proliferation.

Purification of opioid receptor in the presence of sodium ions

Opioid receptor was solubilized from rat brain membranes with a mixture of the detergents CHAPS and digitonin in the presence of protease inhibitors and 1 M NaCl. The solubilized receptor bound mu-opioid agonists and antagonists with affinities similar to those of native membrane receptor. The affinity of solubilized receptor for the agonist PL017 was greatly reduced by GTP gamma S, suggesting the receptor is still associated with G-protein. The solubilized material was passed through an opioid antagonist (10cd) affinity column and a wheat germ agglutinin column, set up in series, to obtain a partially purified receptor preparation. This partially purified material bound mu-agonist with low affinity and the binding affinity was no longer affected by GTP gamma S. The partially purified receptor was further purified by repeating the affinity and lectin chromatography with smaller size column. Binding of opioid antagonist [3H]diprenorphine to the partially or purified receptors was dependent upon the presence of sodium ions. The purified receptor showed saturable and stereospecific binding for opioid ligands, was predominantly of the mu-type, and exhibited as a diffuse band with a medium molecular mass of 62 kD upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The average specific binding activity of the purified receptor was 18.8 +/- 2.3 pmol/micrograms protein, a value close to the theoretical estimation.

A role for the interferon response DNA sequence in directing transcription of the T18d Tla gene

T18d of BALB/c mice is a member of the Tla category of class I genes of the major histocompatibility complex of the mouse and is highly restricted in expression. Deletion analysis implies that an element essential to T18d expression resides within the region -4 to +54. The homologous region of T3d, a Tla gene which normally is not expressed in BALB/c mice, also has promoter activity. Thus the expressibility of T18d vs T3d is unlikely to be due to sequence differences in this region. A DNA-binding protein, factor VI, was found to bind to the region -33 to +54. DNase I footprinting analysis indicated that the DNA fragment 5'-ACTATAGTTTCACTTTTT-3' (+3 to +20) was protected by factor VI. This region includes the interferon response sequence (IRS). Homologous DNA segments of other class I genes, Ld and Dd, competed for factor VI in DNA-protein binding assay with lower affinity as compared with T18d. In mutation analysis, the 3' portion of the IRS is more important than the 5' portion with respect to binding affinity of factor VI and to transcriptional activity in transfected cells. This result signifies a role of IRS in T18d transcription and suggests that the mechanism of T18d transcription might be unusual.

Factors affecting local or regional recurrence in breast cancer

Between 1975 and 1989, 535 patients with infiltrating ductal carcinoma of the breast in various clinical stages were treated by modified radical mastectomy and axillary node clearance, followed by chemotherapy, endocrine therapy or radiotherapy. Median follow-up was 3 years (5 months to 15 years). Fifty-eight local or regional recurrences occurred. The 5-year and 10-year actuarial risks of breast recurrences were 14% +/- 2% and 23% +/- 4%, respectively. Using multivariate analysis with the Cox regression model, the most important multivariate-adjusted independent contributing factors to local or regional breast recurrences were age less than or equal to 40 (p less than 10(-4), relative risk = 2.94), positive lymph nodes greater than 3 (p less than 10(-3), relative risk = 2.57), and multicentricity (p = 0.044, relative risk = 2.73). The overall 5-year survival rate of recurrent patients was 64 +/- 7%, and was significantly worse when breast recurrence occurred in the first 18 months after operation. The multivariate-adjusted relative risk of death for early recurrence was 4.35 (p = 0.04). The unadjusted 5-year survival rate for early recurrence was 58% +/- 1%, and 85% +/- 8% for late recurrence. This study confirms the relationship between young age and low breast control rates. It emphasizes the adverse prognosis of early breast recurrences as compared to the relatively favorable outcome of late recurrences.

Role of 5-lipoxygenase products of arachidonic acid in cell-to-cell interaction between macrophages and natural killer cells in rat spleen

In the present study we performed experiments to reveal the role of 5-lipoxygenase products of arachidonic acid in cell-to-cell interaction between rat peritoneal macrophages and spleen natural killer (NK) cells. Peritoneal macrophages were found to significantly enhance NK cell activity. It was found that the enhancing activity of macrophages was significantly inhibited by the ingestion of highly purified eicosapentaenoic acid-ethyl ester (EPA-E). But direct cytotoxic action of macrophage on target cells (YAC-1) was unchanged by the ingestion of EPA-E. In addition, the depressed enhancing activity of EPA-enriched macrophages (EPA macrophages) was partially, but significantly, restored by the addition of either 10(-10) M leukotriene B4 (LTB4) or 10(-12) M 5-hydroperoxyeicosatetraenoic acid (5-HPETE). The partial restoring effect of 10(-10) M LTB4 was further significantly enhanced by the addition of 5-HPETE. In contrast 5-hydroxyeicosatetraenoic acid (5-HETE) had no modulatory effect on the depressed activity of EPA macrophages. LTB4, 5-HPETE, and 5-HETE had no direct effect on NK cell activity itself. Significantly less amounts of LTB4 and 5-HETE were produced in EPA macrophages as compared with that in control macrophages. The present study indicates that macrophage modulatory action on NK cells can be partly mediated by LTB4 and 5-HPETE, which are produced in macrophages.