Immunomodulatory properties of a strain of Mycobacterium chelonae--II. Qualitative and quantitative stimulation of mouse splenocytes by Mycobacterium chelonae

Intraperitoneal [i.p.] and subcutaneous [s.c.] administration to BALB/C mice with a single dose of 5 mg/kg body weight (wet weight) of live Mycobacterium chelonae (Mch) augmented splenocyte blastogenesis. Similar increases in splenocyte blastogenesis manifested during a single oral administration to mice with 100 mg/kg body weight (wet weight) of this Mycobacterium. When splenocytes issued from these mice are activated by mitogens, a highly significant enhancement of lymphoblastic transformation was observed. On the other hand, multiple oral administrations with 50 mg/kg body weight (wet weight) to Mch/dose did not manifest statistically significant differences in splenocyte blastogenesis as compared to controls. Meanwhile, a highly increased transformation of splenocytes, issued from such mice, is observed in response to lectins and to the mitogenic effect of this microorganism. Splenocyte counts have shown 44.5, 37.6, and 23.2% increases in response to i.p., s.c. and multiple oral administration of this bacterium, respectively, as compared to solvent controls. Repeated s.c. administration of this mycobacterium manifested short lived and weak syndromes of anaphylactic shock during and immediately after the second inoculation of Mch. This phenomenon is not observed during repeated intraperitoneal and oral administrations. In conclusion, parenteral (i.p. and s.c.) and oral administration of Mch stimulates the immune system of mice. This effect is characterised by increased in vivo cell multiplication and by enhanced ex vivo DNA synthesis of murine splenocytes. The need of further studies is eminent to elucidate classes of immunocompetent cells involved in this phenomenon.     

Potentiation of lymphocyte mitogenic responses to concanavalin A by antigen-activated peripheral blood monocytes.

Purified protein derivative (PPD)-stimulated monocytes derived from Mycobacterium bovis-sensitized cattle significantly potentiated lymphocyte mitogenic responses to concanavalin A (conA), as measured by incorporation of [3H] thymidine into cellular DNA. Monocytes were cultured for 24 hours in the presence of PPD, washed thoroughly, and mixed with purified lymphocytes; various doses of conA were added to these cultures, and the cultures were incubated for 4 days and assayed for DNA synthesis. The lymphocyte mitogenic responses to suboptimal, buy not optimal, doses of conA were significantly enhanced by the presence of PPD-activated monocytes from M bovis-sensitized cattle. Treatment nonsensitized cattle with PPD did not result in any significant enhancement of conA-induced lymphocyte mitogenic responses at any dose of conA tested.     

Activation of murine macrophages and lymphocytes by Ureaplasma diversum.

Ureaplasma diversum is a pathogen in the bovine reproductive tract. The objective of the research was to study interactions with macrophages and lymphocytes which might elucidate aspects of pathogenetic mechanisms of this organism. We studied the activation of murine macrophages of C3H/HeN (LPS-responder) and C3H/HeJ (LPS-low-responder) genotype for TNF-alpha, IL-6, IL-1 and nitric oxide production and blastogenic response of C3H/HeJ splenocytes after Ureaplasma diversum stimulation. Live and heat-killed U. diversum induced TNF-alpha, IL-6 and IL-1 in peritoneal macrophage cultures of both C3H/HeN and C3H/HeJ mice in a dose dependent manner. Interferon-gamma modulated the cytokine production, by increasing the production of TNF-alpha, IL-6 and nitric oxide, but IL-1 secretion was only enhanced in C3H/HeJ macrophages stimulated by live ureaplasmas. Supernatant of U. diversum sonicate was mitogenic for murine spleen lymphocytes. The blastogenic response was dose dependent, and stimulation with both U. diversum and Concanavalin A seemed to have an additive effect. These results suggest that U. diversum, similar to other mycoplasmas, activates murine macrophages and lymphoid cells. The studies should be repeated with bovine cells in order to elucidate pathogenetic aspects of inflammation in cattle caused by U. diversum.     

Optimum conditions for the turkey lymphocyte transformation test.

Optimum conditions for turkey lymphocyte transformation tests were determined. Thrice-washed turkey buffy-coat cells obtained after slow centrifugation (40 x g, 10 minutes) responded well to mitogenic stimulation. Turkey lymphocytes isolated on Ficoll-containing separation media largely lost their ability to respond to mitogens. Maximum responses were obtained with 2 x 10(7) lymphoid cells/ml. Responses to the mitogens were greatest when bovine fetal serum was used at a 2.5% concentration or pooled turkey serum and autologous plasma were used at a 1.25% concentration. Higher concentrations of turkey serum or plasma decreased the responses when sub-optimum doses of concanavalin-A (Con A) or phytohemagglutinin-P (PHA-P) were used. Serum-free cultures gave higher stimulation indices than cultures with serum only when sub-optimum doses of Con A or PHA-P were used. Optimum mitogen concentrations varied with individual birds, timing of the culture, temperature of incubation, and serum concentration in the cultures. Responses were usually greatest with final concentrations of 5 micrograms Con A/ml, 10 micrograms PHA-P/ml, and 20 micrograms pokeweed mitogen (PWM)/ml and when the cultures were incubated in 96-well microplates at 40 C in humidified air with 5% CO2 for 40-42 hours with pulsing with 3H-thymidine during the final 16 hours of incubation.     

An evaluation of the mitogenic reactivity of intestinal intraepithelial lymphocytes of chickens.

A colorimetric assay employing MTT (3-[4,5-dimethylthiazole-2-yl], 2-5-diphenyltetrazolium bromide) was used to determine the mitogenic response of intestinal intraepithelial lymphocytes (i-IELs) of chickens to T- and B-cell mitogens. Comparisons between mitogenic responses of i-IELs and peripheral blood lymphocytes (PBLs) were made to examine potential relationships. The results from this study indicated that T-cell mitogens, concanavalin A (Con A), and phytohemagglutinin-P (PHA-P) induced mitogenic stimulation in i-IELs. Although stimulation indexes of both i-IELs and PBLs were similar, the optical densities (ODs) of i-IEL cultures containing Con A or PHA-P were 20- to 50-fold lower than the ODs of PBL cultures containing the same mitogen. The lower conversion of MTT to formazan resulting in lower ODs in i-IEL cultures indicated a lower level of cellular activity in the i-IELs than in the PBLs. The mitogenic responses of both i-IELs and PBLs to Con A and PHA-P were dose dependent. The responsive concentration of Con A for i-IELs was within the range of 25-50 micrograms/ml, whereas the responsive concentration of PHA-P for i-IELs was 50 micrograms/ml. Three days of incubation was found to be adequate to induce a significant (P < 0.05) mitogenic response for both T-cell mitogens. Lipopolysaccharide was unable to induce a mitogenic response in i-IELs, which was attributed to the lack of B cells in the i-IEL population. This technique may prove useful in evaluating and studying the role of i-IELs in local cell-mediated immune responses of the gastrointestinal tract.     

Culture conditions for blastogenic responses of bovine mammary mononuclear cells

Several experimental parameters were examined to determine optimal conditions for proliferative responses of mammary mononuclear cells (MMC) obtained from six nonlactating dairy cows. These parameters were: pre-incubation of cells in medium prior to assay, mitogen concentration, assay incubation time, and type of culture medium. Response variables included viability of cells and the rate of proliferation as assessed by tritiated thymidine incorporation. Pre-incubation of cells in medium had no effect on the proliferative response of MMC. Whereas Concanavalin A (ConA; 3.3 or 6.6 micrograms/ml) and phytohemagglutinin (PHA; 1, 5, 10 micrograms/ml) did stimulate proliferation of MMC, the higher doses did not stimulate greater proliferation than the lower doses of mitogens. The greatest mitogenic response was obtained on days 2 and 3 of incubation. Proliferative responses were significantly higher at all mitogen levels tested in a 50-50 mixture of Rosewell Park Memorial Institute medium 1640 and Liebovitz-15 medium (RPMI/L-15) than in RPMI alone. Viability of MMC was also significantly higher in the RPMI/L-15 medium. To test whether the significant effect of media on blastogenesis was specific for mononuclear cells from the bovine mammary gland, peripheral blood lymphocytes (PBL) from four dairy cows were cultured with ConA and PHA in a mitogen assay in both RPMI and RPMI/L-15. Viability was measured on day of collection and on all culture days. PBL were stimulated equally in both media. PBL viability decreased significantly on day 1 in both RPMI and RPMI/L-15. These results suggest that the optimal culture conditions for blastogenic responses of mammary mononuclear cells and peripheral blood lymphocytes may differ.     

Enhancement of ovine lymphocyte responses: a comparison of selenium and vitamin E supplementation

Lymphocytes of lambs on a low selenium/vitamin E diet were isolated from peripheral blood, and mitogenic responses to phytohaemagglutinin (PHA) tested in the presence of different doses of sodium selenite and emulsified vitamin E added in vitro. An enhancing effect of selenium was observed at doses of 1 ng/ml or less, and reached a plateau at about 10 ng/ml. Toxic effects were evident beyond 1 micrograms/ml. The stimulatory potential of selenium among lambs was inversely related to their ability to respond to PHA in control cultures but was not related to the blood glutathione peroxidase activity of the animals concerned. Optimal doses of vitamin E added to culture (0.15-1.5 micrograms/ml) elevated responses beyond those seen with selenium, but synergistic effects were not apparent. Similar results were obtained when lymphocytes from deficient, myopathic lambs were cultured with serum from lambs supplemented in vivo, and when PHA responses of untreated and treated lambs were compared. Tests with other phytolectins (concanavalin A and pokeweed mitogen) suggested that the two micronutrients exert a differential influence on lymphocyte sub-populations. It was also concluded that the poor lymphocyte responses seen in myopathic lambs can be readily and rapidly reversed by injection of these nutrients, and that prophylaxis is most effective during the first 6 weeks of life.     

A whole blood method for measuring mitogen-induced transformation of sheep lymphocytes

A simple and reproducible micromethod for determination of in vitro mitogenic responses of sheep peripheral blood lymphocytes is described. The test uses (i) whole blood diluted in RPMI 1640 medium to give a cell count of 0.5 x 106-1 x 106 lymphocytes/ml, (ii) mitogens in the range of 5-20 micrograms of phytohaemagglutinin/ml, 20-80 micrograms of lipopolysaccharide/ml or 20-80 microliters of poke weed mitogen/ml, and (iii) a stimulation time of 42 to 90 h. A considerable variation in mitogenic response was observed both between animals and on different occasions in the same animal. Because of the large periodic variation it was suggested that the test should be repeated using blood drawn at different times in order to determine the mitogenic response of an animal.     

Interactions of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) with immune responses of rainbow trout

Chlorinated dioxins, as typified by the most potent isomer, TCDD, are immunosuppressive in mammalian species and can enhance the susceptibility to a number of diseases. In recent years chlorinated dioxins have been detected in fish in many freshwater and marine habitats. Thus far, the effects of these chemicals on the immune responses of fish have not been examined. We studied the influence of TCDD on the defense mechanisms of rainbow trout. Yearling trout were injected intraperitoneally with the vehicle, 0.1, 1.0 or 10 micrograms/kg of TCDD. Interactions with the humoral immune response to sheep red blood cells (SRBC) were assessed by the Jerne plaque assay using head kidney and spleen leukocytes. Serum antibody was measured by complement-mediated lysis of SRBC in a chromium release assay. Effects of TCDD on the cellular immune responses were evaluated by the response of thymic and splenic lymphocytes to Con A and PWM. In addition, the phagocytic activity of peritoneal macrophages was examined in vitro. Trout which received 0.1 or 1.0 micrograms/kg TCDD remained clinically normal, and defense mechanisms were unaltered in these fish. Trout which received 10 micrograms/kg of TCDD became hypophagic and exhibited fin necrosis, ascites and suppression of hematopoiesis. In this treatment group, Con A-induced blastogenesis of thymic and splenic lymphocytes was not significantly changed, however, suppression of the PWM-induced response of splenic lymphocytes occurred. No statistically significant alterations occurred in humoral immune responses, and phagocytic activity of peritoneal macrophages was not decreased. The dose-response curve for various biologic effects of TCDD in the rainbow trout appears different from that in sensitive mouse strains. The 30-day, single-dose, parenteral LD50 for TCDD in the C57BL mouse is 100 micrograms/kg, and TCDD suppresses both cell-mediated and humoral immune responses at 1-2 micrograms/kg in this mouse strain. In the rainbow trout, however, immunosuppression was evident only at doses of TCDD approaching the 80-day, single-dose, parenteral LD50 of 20 micrograms/kg.     

Optimum conditions for the chicken lymphocyte transformation test.

Optimum conditions for chicken (Gallus gallus) lymphocyte transformation tests were determined. Thrice-washed chicken buffy-coat cells obtained after slow centrifugation (40 x g for 10 minutes) responded substantially better to mitogenic stimulation than lymphocytes isolated on separation media containing Ficoll. Maximum responses were obtained with 2 x 10(7) lymphoid cells/ml. Responses to the mitogens were greatest when fetal bovine serum was used at a 5% concentration or pooled chicken serum and autologous plasma were used at a 1.25% concentration. Optimum mitogen concentrations varied with individual birds, timing of the culture, temperature of incubation, and serum concentration in the cultures. When 1.25% chicken serum was used in the cultures, responses were usually greatest with final concentrations of 30-50 micrograms/ml of concanavalin A (Con A) and 30-50 micrograms/ml of phytohemagglutinin-P (PHA-P). The optimum concentration of pokeweed mitogen (PWM) varied from 1 to 40 micrograms/ml among the birds and was practically impossible to establish in general. The incubation in humidified air with 5% CO2 was significantly better at 40 C than at 37 C. The total culture time of 40 hours including pulsing with 3H-thymidine during the final 16 hours of incubation was the best for Con A- and PHA-P-stimulated cells, whereas a longer incubation of 64 hours gave the highest results with PWM stimulations.     

African hamster lymphocytes as a model for immunologic studies.

The mitogenic response of splenic lymphocytes from Mystromys albicaudatus was studied to evaluate the potential of this animal as a model for immunologic research. In response to phytochemagglutinin and concanavalin A, splenic cells from Mystromys, unlike those from mouse strains, incorporate [3H] thymidine optimally in microculture at 10(5) to 2 X 10(5) cells per microculture. Maximum magnitude of incorporation in response to the same doses of mitogen used in mouse splenic lymphocyte microculture is greater than 10(5) cpm. Moreover, this high incorporation at low cell concentration has been observed in cultures from animals ranging from six to 24 months of age. Splenic cells from Mystromys give little or no incorporation with either LPS or PPD in doses mitogenic to mouse lymphocytes. These features of mitogenic response in Mystromys lymphocyte cultures suggest several useful applications to studies of mechanisms of mitogenesis.     

Response to mitogens of chicken splenocytes determined by three methods of measurement

The aim of the present study was to examine whether the 3‐[4,5‐dimethylthiazol‐2‐yl]‐2,5‐diphenyl tetrazolium bromide (MTT) colorimetric assay can be applied to measurement of mitogen‐induced chicken splenocyte activation. Activation was also measured by a ³H‐thymidine uptake assay and a viable cell count assay. Optimal concentrations of mitogens and incubation periods required for maximal responses to mitogens differed between the MTT assay and the viable cell count and thymidine uptake assays. This probably reflects differences in the activities measured by the MTT assay which detects mitochondrial enzyme activity, and the thymidine uptake and viable cell count assays which detect cellular proliferation activity. The validity of the MTT assay was supported by the observation that the mitogen‐induced increase in succinate dehydrogenase activity paralleled the level of mitogen‐induced MTT formazan production. Mitogen concentrations inducing maximal formazan formation in chicken splenocytes were higher than those for chicken peripheral blood lymphocytes reported previously. Results of the present study indicate that mitogen‐induced chicken splenocyte activation could be measured by the MTT colorimetric assay, although mitogen concentrations and incubation periods required for maximal splenocyte activation differed between the MTT assay and the other two assays used in this study.     

A comparative analysis of the mitogenic response of intestinal intraepithelial lymphocytes in various age groups of turkeys.

Mitogenic responsiveness of intestinal intraepithelial lymphocytes (i-IEL) to concanavalin A (Con A), phytohemagglutinin P (PHA-P), and lipopolysaccharide (LPS) from Salmonella typhimurium were evaluated in various age groups of turkeys by a colorimetric blastogenic microassay. Comparisons were made between mitogenic responses of turkey i-IEL and peripheral blood lymphocytes (PBL). The results from this study demonstrated that i-IEL and PBL of turkeys responded to T-cell mitogens, Con A and PHA-P, in every age group examined. The LPS induced a significant mitogenic response in PBL but not in i-IEL of turkeys. The mitogenic responses of turkey i-IEL and PBL to the three mitogens examined were similar to mitogenic responses observed in an earlier study performed by using chicken i-IEL and PBL. The results indicated a difference in mitogenic response between different age groups. An increase was found in mitogenic response of i-IEL to both T-cell mitogens from 3 days of age to 1 wk of age, whereas mitogenic response of PBL to all three mitogens declined significantly from 1 day of age to 3 days of age. The highest mitogenic response of i-IEL to T-cell mitogens was observed at 1 wk of age. The highest mitogenic response of PBL to both T-cell mitogens was observed at 1 day of age and the highest PBL response to LPS was observed at 16 wk of age. The mitogenic response induced by PHA-P provided less variability between age groups than the mitogenic response induced by Con A.     

In vitro stimulation of bovine peripheral blood lymphocytes: effect of short-term storage of blood prior to lymphocyte culture

Storage of peripheral blood from Mycobacterium bovis-sensitized cattle from 1 to 48 hours at 4, 22, and 37 C was shown not to alter markedly the lymphocyte blastogenic response to M bovis-purified protein derivative. Concanavalin A-induced lymphocyte mitogenic responses were unaffected by storage of blood for 1, 24, or 48 hours at 22 C and 37 C; however, storage of blood for 48 hours at 4 C significantly lowered (P less than 0.05) mitogenic responses to concanavalin A, as compared with responses to blood kept at 22 C. Mononuclear cell recovery from stored blood at all temperatures was markedly less than that from freshly drawn blood samples. Cell recoveries were most affected by storage of blood at 4 C and 37 C.     

Comparative studies of mitogen- and antigen-induced lymphocyte proliferation in four captive rhinoceros species.

Cellular immune function in four rhinoceros species was evaluated by way of in vitro lymphocyte proliferation responses to mitogenic and antigenic stimuli to establish normative data on white blood cell activity for each species and to identify species-specific differences that might help explain the predisposition of black rhinoceroses (Diceros bicornis) to disease. A cross section of the U.S. rhinoceros population encompassing all four captive species was sampled, including the Sumatran rhinoceros (Dicerorhinus sumatrensis) (n = 3); Indian rhinoceros (Rhinoceros unicornis) (n = 4); African black rhinoceros (n = 16); and African white rhinoceros (Ceratotherium simum) (n = 10). Of the four species evaluated, African black rhinoceroses exhibited the weakest (P < 0.05) lymphocyte proliferative responses to the mitogens: pokeweed (0.1 microg/ml), phytohemagglutinin (0.3 microg/ml), and concanavalin A (5.0 microg/ml). Total cell density at the end of culture was only 70% of that achieved with lymphocytes isolated from African white rhinoceroses, Indian rhinoceroses, and Sumatran rhinoceroses. However, lymphocyte response to bacterial endotoxin lipopolysaccharide was similar (P > 0.05) across species. Antigenic stimulation produced much weaker responses than mitogenic stimulation. No differences (P > 0.05) were observed among rhinoceros species in response to 1 and 10 microg/ml of Leptospira icterohemorrhagiae or Leptospira gryppotyphosa. Lymphocytes from African white rhinoceroses proliferated weakly in the presence of Aspergillus fumigatus filtrate, whereas lymphocytes from the southern black rhinoceros subspecies appeared slightly suppressed in the presence of increasing doses (0.1, 1, and 10 microg/ml) of Aspergillus filtrate. This comparative data set characterizing lymphocyte proliferation in the rhinoceros reveals several differences in immune cell responses among rhinoceros species and provides some evidence that lymphocytes of captive African black rhinoceroses are less vigorous than those of the other rhinoceros species.     

Immunosuppression of in vivo and in vitro lymphocyte responses in swine induced by Trichinella spiralis or excretory-secretory antigens of the parasite.

The in vivo and in vitro effects of Trichinella spiralis excretory-secretory (ES) antigens on porcine peripheral blood lymphocyte (PBL) responses induced with mitogens (phytohemagglutinin, PHA; concanavalin A, Con A; pokeweed mitogen, PWM) or unrelated antigen (Protein A) were studied to determine whether ES antigens depress lymphocyte responses in experimental swine trichinosis, and/or if this response was manifested after lymphocytes from infected pigs had been pretreated with ES antigens. Additionally, the range of inhibition of lymphocyte responses was tested in parasite-free pigs using different doses of ES antigens and compared with the responsiveness of control cultures from the same animals. The responses of lymphocytes from pigs inoculated with 4 x 10(3) muscle larvae (ML) were strongly depressed (P < 0.05) at post-inoculation days (PID) 7 (after stimulation with PHA), 14, 35 (Con A or PWM), and 49 (PWM). At PID 56 and 63 the lymphocytes from T. spiralis-infected pigs responded better (P < 0.05) to all three mitogens than those from non-infected controls. After 7 weeks post-inoculation, PBL which were pretreated with 10 or 250 micrograms ml-1 of ES antigens showed significantly weaker (P < 0.05, P < 0.001) responses to PWM or PHA, respectively, than those from non-infected animals. The responsiveness of lymphocytes from both groups of pigs to Protein A was not affected by the pretreatment with ES antigens in vitro. The responses of lymphocytes from the parasite-free pigs induced by PHA, PWM or Protein A were strongly depressed (P < 0.01) after in vitro pretreatment regardless of the dose of ES antigens (5, 10, 15, or 20 micrograms ml-1) applied.     

Immunophysiological studies of interleukin-2 and canine lymphocytes.

Interleukin-2-dependent pathways of lymphocyte activation were investigated in canine peripheral blood lymphocytes (PBL) following stimulation with T-cell mitogens including phytohemagglutinin, phorbol ester (TPA), calcium ionophore (ionomycin), and human recombinant interleukin-2 (hrIL-2). The ability of the stimulated cells to produce interleukin-2 (IL-2) was determined using murine indicator cell lines. IL-2 receptor expression by mitogen-stimulated canine PBL was confirmed by the binding of hrIL-2 with high affinity, and with characteristics comparable to those of the human and murine IL-2 receptor. Examination of serum and PBL from two dogs that were treated with hrIL-2 and human recombinant tumor necrosis factor for systemic mast cell tumors showed that in one dog, IL-2 could be measured in the serum. Concurrently, the in vitro mitogenic response of this dog's PBL to hrIL-2 occurred earlier, possibly reflecting an increase in the relative number of IL-2-responsive cells within the PBL population.     

Effects of Pasteurella haemolytica lipopolysaccharide on selected functions of bovine leukocytes

Lipopolysaccharide (LPS) was obtained from Pasteurella haemolytica serotype 1, using phenol-water extraction, and was evaluated for its ability to modify the biological activity of bovine leukocytes. The LPS was not toxic to polymorphonuclear leukocytes (PMN). The LPS preparation had little effect on random migration of PMN or mononuclear leukocytes (MNL), but caused a 2.5- to 3- fold increase in migration of cells within a whole peripheral blood leukocyte preparation. Phagocytosis of [125I]-labeled Staphylococcus aureus by PMN decreased with low (2.5 micrograms/10(6) cells) and high (65 micrograms/10(6) cells) concentrations of LPS and increased with moderate concentrations of LPS (5 to 25 micrograms/10(6) cells). The LPS enhanced nitroblue tetrazolium reduction by PMN. Moderate LPS concentrations (25 to 50 micrograms/10(6) cells) were mitogenic for MNL, whereas high LPS concentrations (300 micrograms/10(6) inhibited [3H]thymidine incorporation by MNL.     

Evaluation of the interaction of mu and kappa opioid agonists on locomotor behavior in the horse.

This study was designed to determine the interactive effects of mu and kappa opioid agonists on locomotor behavior in the horse. Three doses of a mu agonist, fentanyl (5, 10, 20 micrograms/kg) and a kappa agonist U50,488H (30, 60, 120 micrograms/kg) were administered in a random order to six horses. Locomotor activity was measured using a two minute footstep count. Each dose of U50,488H was then combined with 20 micrograms/kg of fentanyl to determine the interactive effects of the drugs on locomotor activity. A significant increase in locomotor activity was seen with 20 micrograms/kg of fentanyl and all the drug combinations. The combination of U50,488H with fentanyl resulted in an earlier onset of locomotor activity. At the highest doses of the combination (U50,488H 120 micrograms/kg, fentanyl 20 micrograms/kg), the duration of locomotor activity was significantly increased when compared to the other doses. We conclude that locomotor activity is maintained or enhanced in horses when a receptor specific kappa agonist is combined with a mu receptor agonist.     

Effect of aztreonam upon human polymorphonuclear leukocyte functions.

Aztreonam (SQ 26,776), a new synthetic monobactam with an excellent antibacterial spectrum was analyzed in vitro. In this paper, the effect of aztreonam on the phagocytic process of human neutrophils isolated from fifteen healthy volunteers was studied. Chemotaxis was not modified with aztreonam at any of the doses used (10, 20, 40, 60, 80 and 100 micrograms/ml). On the other hand, this antibiotic at 100 micrograms/ml significantly increases (P less than 0.05) Candida albicans ingestion as well as their digestion by neutrophils at 10 and 100 micrograms/ml.