Generation of oxygen free radicals from blood eosinophils from asthma patients after stimulation with PAF or phorbol ester

Eosinophils (EOS) may play an important role in the pathophysiology of bronchial asthma because they can release oxygen free radicals and several basic proteins which are cytotoxic to bronchial epithelium. We have studied the response of EOS isolated from the blood of atopic subjects with symptoms of asthma (AS, n = 7) or rhinitis (AR, n = 4) or without symptoms (AA, n = 5) and of subjects with the hypereosinophilic syndrome (HES, n = 5). EOS were separated using metrizamide density gradients and activated in vitro with platelet-activating factor (PAF, 100 nM) or phorbol 12-myristate-13-acetate (PMA, 100 nM). Oxygen free radical generation was assessed by a lucigenin-enhanced chemiluminescence (CL) assay. EOS purity was 83 +/- 1.7% (mean +/- SEM) with greater than 95% viability. Background CL responses of EOS from HES were significantly higher than those from AA (p less than 0.01) and AR (p less than 0.05). Normodense EOS from AS (PAF-induced CL = 90 +/- 27 mV) were more responsive to PAF than were those from AR (17 +/- 13 mV, p less than 0.01) and from AA (23 +/- 14 mV, p less than 0.01). Similar results were obtained with PMA. Hypodense EOS from HES subjects were as responsive as normodense EOS from AS to PMA and PFA. Thus, EOS from AS have an enhanced potential for activation, particularly by PAF; this may represent an important mechanism for the perpetuation of the inflammatory response in asthma, since EOS can also release PAF.

Generation of oxygen free radicals from blood eosinophils from asthma patients after stimulation with PAF or phorbol ester

Eosinophils (EOS) may play an important role in the pathophysiology of bronchial asthma because they can release oxygen free radicals and several basic proteins which are cytotoxic to bronchial epithelium. We have studied the response of EOS isolated from the blood of atopic subjects with symptoms of asthma (AS, n = 7) or rhinitis (AR, n = 4) or without symptoms (AA, n = 5) and of subjects with the hypereosinophilic syndrome (HES, n = 5). EOS were separated using metrizamide density gradients and activated in vitro with platelet-activating factor (PAF, 100 nM) or phorbol 12-myristate-13-acetate (PMA, 100 nM). Oxygen free radical generation was assessed by a lucigenin-enhanced chemiluminescence (CL) assay. EOS purity was 83 +/- 1.7% (mean +/- SEM) with greater than 95% viability. Background CL responses of EOS from HES were significantly higher than those from AA (p less than 0.01) and AR (p less than 0.05). Normodense EOS from AS (PAF-induced CL = 90 +/- 27 mV) were more responsive to PAF than were those from AR (17 +/- 13 mV, p less than 0.01) and from AA (23 +/- 14 mV, p less than 0.01). Similar results were obtained with PMA. Hypodense EOS from HES subjects were as responsive as normodense EOS from AS to PMA and PFA. Thus, EOS from AS have an enhanced potential for activation, particularly by PAF; this may represent an important mechanism for the perpetuation of the inflammatory response in asthma, since EOS can also release PAF.

Distribution and molecular form of immunoreactive big endothelin-1 in porcine tissue

In the present study a specific and sensitive radioimmunoassay for big endothelin-1 was developed. Half maximal inhibition of binding of radioiodinated big endothelin-1 was observed at 58 pg/tube and big endothelin-1 was detectable as low as 2 pg/tube. With this assay, the regional distribution of big endothelin-1 was determined in porcine tissue and compared to the distribution of an immunoreactive endothelin. Considerable amount of immunoreactive big endothelin-1 was observed in the aortic intima (0.84 +/- 0.094 pg/mg wet tissue; mean +/- S.D.) and the lung (0.47 +/- 0.055), but there was a low concentration in other tissue including the kidney inner medulla, which has been shown to be abundant in immunoreactive endothelin. Furthermore the molecular form of immunoreactive big endothelin-1 in aortic intima was found to be big ET-1[1-39], but the molecular form of major immunoreactive big endothelin-1 in the lung is big endothelin-1[22-39] with big endothelin-1[1-39] being minor.

Beta 2-adrenergic receptors on eosinophils. Binding and functional studies

We have studied the binding characteristics and functional effects of beta-adrenoceptors on human and guinea pig eosinophils. We determined the binding of the beta-antagonist radioligand [125I]pindolol (IPIN) to intact eosinophils obtained from the peritoneal cavity of guinea pigs and from blood of patients with eosinophilia. Specific binding was saturable, and Scatchard analysis showed a single binding site with a dissociation constant (Kd) of 24.6 pM and maximal number of binding sites (Bmax) of 7,166 per cell. ICI 118,551, a beta 2-selective antagonist, inhibited IPIN binding with a Ki value of 0.28 nM and was approximately 5,000-fold more effective than the beta 1-selective antagonist, atenolol. Isoproterenol increased cAMP levels about 5.5-fold above basal levels (EC50 = 25 microM); albuterol, a beta 2-agonist, behaved as a partial agonist with a maximal stimulation of 80%. Binding to human eosinophils gave similar results with a Kd of 25.3 pM and a Bmax corresponding to 4,333 sites per cell. Incubation of both human and guinea pig eosinophils with opsonized zymosan (2 mg/ml) or with phorbol myristate acetate (PMA) (10(-8) and 10(-6) M) resulted in superoxide anion generation and the release of eosinophil peroxidase; albuterol (10(-7) to 10(-5) M) had no inhibitory effect on the release of these products. Thus, eosinophils from patients with eosinophilia and from the peritoneal cavity of guinea pigs possess beta-receptors of the beta 2-subtype that are coupled to adenylate cyclase; however, these receptors do not modulate oxidative metabolism or degranulation. The possible therapeutic consequences of these observations to asthma are discussed.

The effects of activated eosinophils and neutrophils on guinea pig airway epithelium in vitro

Epithelial shedding is a characteristic feature of asthmatic airways and has been attributed to eosinophil products. We have examined the interaction of purified intraperitoneal guinea pig eosinophils with or without platelet-activating factor (PAF, 10(-7) M) or lyso-PAF (10(-7) M) with guinea pig tracheal epithelium in vitro. At 0, 4, 14, and 24 h, the percentage of ciliation of the tracheal circumference (CTC) was measured by light microscopy and the ciliary beat frequency (CBF) by photometry. PAF-activated eosinophils (50 x 10(6) cells/ml) disrupted the epithelium, mean CBF and CTC being reduced by 77.8 +/- 5.8% (mean +/- SEM; P less than 0.001 versus control) and 94.2 +/- 1.4% (P less than 0.001) over 24 h, respectively. PAF (10(-7) M) alone had no significant effect. Lyso-PAF with eosinophils (50 x 10(6) cells/ml) also reduced mean CBF and CTC but to a lesser extent. Eosinophils alone also led to a reduction of 36.2 +/- 11.4% in mean CBF and 53.0 +/- 15.5% in CTC, but these changes were not significant. The PAF antagonist, WEB 2086 (10(-6) M), significantly inhibited the mean CBF and CTC reduction due to PAF-activated eosinophils by 61.5 +/- 17.2% (P less than 0.01) and 20.8 +/- 6.5% (P less than 0.05), respectively. In addition, catalase (1,125 U/ml) partially inhibited the mean CBF and CTC reduction induced by PAF-activated eosinophils. Intraperitoneal neutrophils (PMN) (50 x 10(6) cells/ml) also disrupted epithelium but to a lesser extent (24-h reduction: 34.2 +/- 12.7% for mean CBF and 60.2 +/- 13.2% for CTC, respectively). Stimulation with PAF (10(-7) M) had no further effect. Marked exfoliation of the epithelial layer was observed after 14 h of incubation with activated eosinophils. We concluded the PAF-activated eosinophils are capable of grossly disrupting ciliated epithelium and may contribute to epithelial damage observed in asthma.

Density heterogeneity of eosinophil leucocytes: induction of hypodense eosinophils by platelet-activating factor

We have examined the induction of hypodense eosinophils by platelet-activating factor (PAF), a mediator which may be involved in eosinophil activation in allergic diseases. Guinea-pig eosinophils were incubated with buffer or PAF and applied to continuous Percoll density gradients. Cellular density ranged from 1.0142 to 1.1369 g/ml. Peak eosinophil density in control was 1.0887 +/- 0.0008 g/ml (mean +/- SEM), and 91.1 +/- 1.4% of eosinophils were distributed between 1.0810 and 1.1000 g/ml. Preincubation of eosinophils with PAF(10(-7) M) resulted in a time-dependent and non-cytolytic increase of the number of hypodense eosinophils, with peak densities after incubation for 1 hr and 2 hr of 1.0834 +/- 0.0014 (n = 4, P less than 0.05) and 1.0755 +/- 0.0007 g/ml (n = 6, P less than 0.01), respectively. After incubation for 2 hr, 82.0 +/- 4.9% (n = 6) eosinophils showed a density lower than 1.080 g/ml. Lyso-PAF, the inactive precursor and metabolite of PAF, at a concentration of 10(-7) M had no effect on cell density. The specific PAF receptor antagonist WEB 2086 (10(-6) M) inhibited the PAF-induced density shift by 87.0 +/- 5.3%. Our results demonstrate that a single mediator is able to induce the formation of hypodense eosinophils. We conclude that the appearance of hypodense eosinophils in allergic diseases such as asthma may occur, at least in part, in response to inflammatory mediators which activate these cells.

Effect of theophylline and adenosine on eosinophil function

Eosinophils may play a critical role in asthma and bronchial hyperresponsiveness, yet the effect of theophylline on their function is not certain. We have examined the effects of theophylline on opsonized zymosan-induced superoxide anion (O2-) release from guinea pig eosinophils harvested from the peritoneal cavity and from human eosinophils obtained by differential centrifugation of blood from patients with peripheral eosinophilia. Theophylline at high concentration (10(-3) M) inhibited O2- release by 27.6 +/- 9.4% (mean +/- SEM, p less than 0.05), whereas at clinically relevant concentrations (10(-6) and 10(-5) M), it significantly potentiated this by 26.8 +/- 9.9% (p less than 0.05) and 36.9 +/- 6.3% (p less than 0.01), respectively. 8-phenyltheophylline (10(-7) to 10(-3) M), which like theophylline inhibits adenosine receptors but does not inhibit phosphodiesterase activity, produced potentiation at all concentrations. Preincubation of eosinophils with adenosine deaminase (0.1 U/ml) enhanced O2- release by 72.4 +/- 15.2% (p less than 0.01), whereas addition of adenosine (3 x 10(-8) to 10(-6) M) reversed the potentiation induced by theophylline (10(-5) M) in a concentration-dependent manner. Inhibition was greater with the A2-selective analog N-ethylcarboxamide adenosine than the A1-selective analog phenylisopropyladenosine, suggesting that A2-receptors are involved. In human eosinophils we have demonstrated a similar effect of theophylline and adenosine on O2- release. Our results indicate that therapeutic concentrations of theophylline may potentiate eosinophil activation in vivo by competing with circulating adenosine for eosinophil A2-receptors. This would be consistent with the lack of effect of theophylline on bronchial hyperresponsiveness, which may be related to eosinophilic inflammation.

Evidence for two platelet activating factor receptors on eosinophils: dissociation between PAF-induced intracellular calcium mobilization degranulation and superoxides anion generation in eosinophils

We have compared platelet activating factor (PAF)-induced eosinophil peroxidase (EPO) release and intracellular calcium mobilization with superoxide anion (.O2-) generation from guinea pig eosinophils. EPO release and Ca2+ mobilization occurred at lower concentrations of PAF (EC50 values of 1.3 nM and 11.5 nM, respectively) while .O2- production was observed at higher concentrations (EC50 of 31.7 microM). Receptor characterization with the competitive PAF antagonist, WEB 2086, gave pA2 values of 8.5 and 8.3 for EPO enzyme release and rise in [Ca2+]i, respectively, and 5.8 for the .O2- production. In addition, PAF-induced degranulation and elevation of [Ca2+]i were dependent on extracellular Ca2+ whereas PAF-stimulated .O2- generation was dependent on the presence of extracellular Mg2+ ions. These results suggest the existence either of two subtypes of the PAF receptor or a single receptor that can exist in one of two affinity states on guinea pig eosinophils.

Stimulation of degranulation from human eosinophils by platelet-activating factor

Platelet-activating factor (PAF) is a highly active mediator which has been implicated in allergic inflammation and bronchial asthma, possibly by interacting with eosinophils. We have examined the effect of PAF on activation of purified human eosinophils as measured by degranulation (eosinophil peroxidase, eosinophil cationic protein, arylsulfatase B, beta-glucuronidase, and alkaline phosphatase) and oxidative metabolism (superoxide anion production). PAF induced enzyme release at concentrations ranging from 1 pM to 10 microM in a rapid (t1/2 5 to 8 min), Ca2+-dependent and noncytotoxic manner from both the specific and small granules, whereas its biologic precursor and metabolite, lyso-PAF, had no effect. For all enzymes, maximal enzyme release occurred at 100 nM PAF with a mean ED50 value of 1.47 +/- 0.4 nM. At this concentration the mean percentage of total enzyme release by PAF from specific granules was 20.3 +/- 1.6% (17.9% for eosinophil peroxidase, 20.6% for beta-glucuronidase, 22.4% for alkaline phosphatase) and 28.8 +/- 2.2% from small granules (arylsulfatase B). Calcium ionophore A23187, PMA, and opsonized zymosan also induced eosinophil degranulation but their peak effect after 10-min incubation with maximal release 14.7%, 12.9%, or 14.1%, respectively, was lower when compared with PAF. Incubation of eosinophils with the PAF-antagonist WEB 2086 led to a parallel shift of the dose-response curve to the right, indicating a competitive antagonism. PAF also caused generation of superoxide anions by human eosinophils but this occurred at higher concentrations of PAF (1 microM to 30 microM) with an ED50 of 8.4 +/- 0.9 microM. Again, this effect was competitively inhibited by WEB 2086. These studies demonstrate that PAF activates human eosinophils to release granule constituents and generate superoxide anions. Since both PAF and eosinophil products are associated with pathogenesis of bronchial asthma our findings may be of particular pathophysiologic relevance.

Stimulation of degranulation from human eosinophils by platelet-activating factor

Platelet-activating factor (PAF) is a highly active mediator which has been implicated in allergic inflammation and bronchial asthma, possibly by interacting with eosinophils. We have examined the effect of PAF on activation of purified human eosinophils as measured by degranulation (eosinophil peroxidase, eosinophil cationic protein, arylsulfatase B, beta-glucuronidase, and alkaline phosphatase) and oxidative metabolism (superoxide anion production). PAF induced enzyme release at concentrations ranging from 1 pM to 10 microM in a rapid (t1/2 5 to 8 min), Ca2+-dependent and noncytotoxic manner from both the specific and small granules, whereas its biologic precursor and metabolite, lyso-PAF, had no effect. For all enzymes, maximal enzyme release occurred at 100 nM PAF with a mean ED50 value of 1.47 +/- 0.4 nM. At this concentration the mean percentage of total enzyme release by PAF from specific granules was 20.3 +/- 1.6% (17.9% for eosinophil peroxidase, 20.6% for beta-glucuronidase, 22.4% for alkaline phosphatase) and 28.8 +/- 2.2% from small granules (arylsulfatase B). Calcium ionophore A23187, PMA, and opsonized zymosan also induced eosinophil degranulation but their peak effect after 10-min incubation with maximal release 14.7%, 12.9%, or 14.1%, respectively, was lower when compared with PAF. Incubation of eosinophils with the PAF-antagonist WEB 2086 led to a parallel shift of the dose-response curve to the right, indicating a competitive antagonism. PAF also caused generation of superoxide anions by human eosinophils but this occurred at higher concentrations of PAF (1 microM to 30 microM) with an ED50 of 8.4 +/- 0.9 microM. Again, this effect was competitively inhibited by WEB 2086. These studies demonstrate that PAF activates human eosinophils to release granule constituents and generate superoxide anions. Since both PAF and eosinophil products are associated with pathogenesis of bronchial asthma our findings may be of particular pathophysiologic relevance.

Characterization of platelet-activating factor-induced elevation of cytosolic free calcium concentration in eosinophils

In order to evaluate the role of calcium in the activation processes in eosinophils induced by platelet-activating factor (PAF), we investigated the changes in free cytoplasmatic Ca2+ concentration using fura-2. PAF causes a rapid and transitory rise of the intracellular free calcium ion concentration [( Ca2+]i) in purified guinea pig eosinophils of approx. 1000 nM above a basal level of 120.7 +/- 36.5 nM (n = 10). The effect was dose-related with a maximum rise at 1000 nM PAF and an EC50 of 17.4 nM and specifically inhibited by the PAF antagonist WEB 2086 with an IC50 of 95.5 nM. WEB 2086 did not affect either the leukotriene B4- or the fMet-Leu-Phe-induced elevation of [Ca2+]i. The response to PAF was dependent on external Ca2+ as it was significantly inhibited by EGTA (85.6 +/- 5.4%) and Ni2+ (95.8 +/- 2.1%) but not by the dihydropyridine antagonist nimodipine. We conclude that Ca2+ entry via receptor-operated Ca2+ channels may be involved in PAF-induced degranulation of eosinophils.

Changes in airway responsiveness and beta- and alpha-1-adrenergic receptors in the lungs of guinea pigs with experimental asthma

The effects of inhaled allergen on airway responsiveness and on beta- and alpha-1-adrenergic receptors on lung membrane were investigated in guinea pigs. After measuring the respiratory threshold to histamine (RT-HIS), one group of guinea pigs passively sensitized for ovalbumin was challenged by allergen inhalation (challenged group). Measurement of the RT-HIS 24 h following challenge revealed a significant decrease from 687 micrograms/ml (mean, n = 16) to 407 micrograms/ml (P less than 0.05). In addition the RT-HIS 24 h after challenge was also significantly lower in the challenged group than in controls (n = 9, P less than 0.05). The density of beta-adrenergic receptors on the lung membrane of the challenged group was 594 +/- 32 (mean +/- SE) fmol/mg protein (n = 11) compared with 712 +/- 24 fmol/mg protein (n = 9) in the controls, a statistically significant difference (P less than 0.05). A significant correlation was found between the RT-HIS and density of beta-adrenergic receptors. From these results, we concluded that the exaggerated airway responsiveness 24 h after allergen challenge is in part due to a decrease in the density of beta-adrenergic receptors. There was no difference in the density of alpha-1-adrenergic receptors nor a significant correlation between the RT-HIS and the number of alpha-1-adrenergic receptors in the challenged vs. the control groups.

Platelet-activating factor induces eosinophil peroxidase release from purified human eosinophils

The degranulation response of purified human eosinophils to platelet-activating factor (PAF) has been studied. PAF induced release of eosinophil peroxidase (EPO) and beta-glucuronidase from highly purified human eosinophils with an EC50 of 0.9 nM. The order of release was comparable with that induced by phorbol myristate acetate (PMA). The new specific PAF antagonist 3-[4-(2-chlorophenyl)-9-methyl-H-thieno[3,2-f] [1,2,4]triazolo-[4,3a][1,4]-diazepin-2-yl](4-morpholinyl)- 1-propane-one (WEB 2086) inhibited the PAF-induced enzyme release by human eosinophils in a dose-dependent manner. The viability of eosinophils were unaffected both by PAF and WEB 2086. The results suggest that PAF may amplify allergic and inflammatory reactions by release of preformed proteins from eosinophil granules.

Disposition of moxalactam and N-methyltetrazolethiol in rats and monkeys

The disposition of moxalactam (MOX) and N-methyltetrazolethiol (NMTT) in rats and monkeys after intravenous injection was investigated, focusing on the in vivo liberation of NMTT, by using [NMTT-14C]MOX and [14C]NMTT. After [NMTT-14C]MOX injection, MOX levels in plasma quickly became high in both rats and monkeys and then declined, with half-lives at the beta phase of 18.8 and 67.1 min, respectively. The levels of NMTT liberated from MOX were much lower than those of MOX, but the apparent elimination was significantly slow. The levels of MOX and NMTT in rat liver were almost comparable but lower than those in plasma. With [14C]NMTT administration, the level of NMTT in plasma declined, with half-lives at the beta phase of 21.5 min in rats and 54.0 min in monkeys. After [NMTT-14C]MOX injection, most of the radioactivity was excreted in urine as MOX, with 11% of the dose in rats and 8% of the dose in monkeys eliminated as NMTT until 24 h. Total biliary excretion was 26% of the injected radioactivity in rats, and most of it was due to MOX. In one monkey, the total biliary excretion was only 0.2% of the injected radioactivity. With [14C]NMTT administration, most radioactivity was excreted in the urine as unchanged NMTT in both animals. Oral administration in rats showed that part of the biliary-excreted MOX was degraded to NMTT in the intestine and then absorbed. Repeated administration of [NMTT-14C]MOX to rats did not change the levels of MOX and NMTT in plasma or liver nor did it change the excretion profiles. Thus, accumulation of MOX and NMTT did not occur.

Effect of thromboxane A2 synthetase inhibitor on immediate-type hypersensitivity reactions

The effect of the thromboxane (TX) A2 synthetase inhibitor, OKY-046, on human leukocyte histamine release and bronchial hypersensitivity in asthmatic subjects was evaluated. It was found that OKY-046 inhibited IgE- and Ca2+ ionophore A23187-mediated leukocyte histamine release in a dose-dependent fashion (IC50: 1.0 and 3.0 X 10(-3) M, respectively) and that OKY-046 could diminish bronchial hypersensitivity, determined by leukotriene D4 inhalation, following a 2-week oral medication. These data suggest that the TXA2 synthetase inhibitor can produce favorable effects upon the course of immediate-type hypersensitivity reactions.

Experimental model of anaphylaxis-induced beta-adrenergic blockade in the airways

The influence of an anaphylactic challenge on the relaxing effects of isoproterenol, prostaglandin E1 (PGE1), forskolin, and aminophylline was examined using an isolated tracheal muscle preparation from ovalbumin (OA)-sensitized guinea pigs. As compared with histamine (4 X 10(-5) M) challenge, an anaphylactic challenge with OA (5 micrograms/mL) caused a rightward shift of the concentration-response curves for isoproterenol, PGE1, and forskolin but not for aminophylline. Their 50% effective concentrations were increased by about 1.7- to 2.8-fold of the histamine challenged preparations. These results indicate that anaphylactic challenge of the sensitized guinea pig tracheal muscle diminishes relaxing effects of isoproterenol, PGE1, and forskolin but not aminophylline. Possible mechanisms of these subsensitivities may involve both impaired coupling mechanism between receptor and adenylate cyclase and decreased adenylate cyclase activity, rather than their receptor numbers or affinity.

[Effects of cefoperazone on respiratory infections of patients of advanced age and/or with underlying respiratory diseases]

Respiratory infections of 19 subjects of advanced age and/or with underlying respiratory disease were treated with cefoperazone (CPZ) and its clinical effects were studied. Sixteen subjects suffered from respiratory tract infection and 3 subjects had pneumonia. The age of the subjects ranged from 39 to 77 years with the mean of 63.8, 7 of them being more than 70 years of age. The underlying respiratory diseases included chronic pulmonary emphysema in 6 subjects, diffuse panbronchiolitis in 3, bronchiectasis in 3, silicosis in 2 and one each of chronic bronchitis, pulmonary fibrosis, lung cancer and old pulmonary tuberculosis. One case, 75 years of age, had renal insufficiency. The daily dose of CPZ was 4 grams in 18 of the 19 subjects and the duration of administration ranged 5 to 22 days. The remaining 1 subject received 2 g of CPZ daily for 6 days. Clinical effects were judged from the changes in fever, cough, amount of sputum, dyspnea, rales, cyanosis, chest X-ray, white blood cell counts, CRP, erythrocyte sedimentation rates and results of sputum culture. Clinical effects were good in 16 subjects, fair in 1, and poor in 2. Bacteriological follow-up was carried out in 13 subjects. Infecting bacteria were eliminated from 5 subjects, reduced in 2 and, in 4 subjects, they were replaced by other bacteria. In 1 subject, P. aeruginosa was isolated from sputum even after the treatment with CPZ, and in another subject H. influenzae relapsed immediately after the cessation of the CPZ treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

[Clinical and experimental study of the host defense mechanism from the aspect of tumor immunology]

The host defense mechanism was fundamentally and clinically investigated from the aspect of tumor immunology. The behavior of macrophages in the immune systems of experimental animals demonstrated different patterns of response in the bone marrow, peritoneal cavity and spleen, respectively. It was doubtless that the spleen occasionally exerted an immunosuppressive action. Ectopic immunization of syngeneic rats with normal liver cells resulted in specific inhibition of the growth of the tumor cells (AH-I30) derived from liver. This seemed to strongly suggest a local immune response. In clinical cases, the host defense mechanism was found to collapse due to surgical intervention, malnutrition and immunosuppressive substances. The relation between complements and host defense mechanism has been controversial. Our studies indicated the serum complement level to be the most reliable parameter for understanding the host defense mechanism. Since the combination of immunostimulants and anticancer drugs is likely to induce anticancer drugs to exert an adverse effect depending on the time of such combination, timing of combined administration of drugs should be chosen with great care.