Acquired resistance to migrating larvae of Ascaris suum in young pigs by repeated drug-abbreviated infections.

Cross-bred 3- and 8-wk-old pigs were used to test whether drug-abbreviated infections with Ascaris suum can stimulate acquired resistance to challenge. During the immunization period, both age groups of animals were infected with increasing numbers of A. suum eggs (500, 1,000, 2,000, 5,000, 10,000, and 20,000) at 7-day intervals while the pigs were receiving pyrantel tartrate in the feed. Two days after the last infective dose, animals were placed on unmedicated feed for 8 days and then challenged with 10,000 eggs. All pigs were killed 7 days after challenge, and milk spots on the livers and larvae recovered from the lungs were counted. Larval recoveries from lungs of the immunized animals were significantly smaller than those from the unimmunized animals in both age groups, suggesting that the pigs were capable of acquiring strong resistance to parasitic infections. In immunized animals, challenge infection did not contribute significantly to milk spot formation. The number of milk spots was significantly greater in the older animals, indicating that milk spot formation may be age related.

Evaluation of pyrantel-tartrate abbreviated Ascaris suum infections for the development of resistance in young pigs against migrating larvae.

Crossbred young pigs were used to test whether abbreviated infections with eggs of Ascaris suum can stimulate the acquisition of resistance to challenge. Weanling pigs from an Ascaris-free colony were kept free of A. suum until they were divided into groups at the age of 7-8 weeks. The experimental animals received pyrantel tartrate during the period when they were being exposed to increasing numbers of infective A. suum eggs and challenged 10 days after the last infective dose. Liver milk-spot counts and larval recoveries from the lungs indicated that the strongest resistance was acquired by the animals that received the drug continuously for 6 weeks while being exposed to six weekly infective egg doses. The data do not suggest any drug-related suppression of the resistance response to A. suum infection.

Phagocytic functions of pulmonary alveolar macrophages in genetically selected lean and obese swine and the effects of exogenous linolenic acid upon cell function.

Alveolar macrophages from genetically selected obese and lean swine were compared for in vitro phagocytic capabilities, using Fc (gamma)- and C3-mediated phagocytosis. Cells from obese pigs were significantly more effective at Fc (gamma)-mediated phagocytosis than those from lean pigs, both for percentage of total cells phagocytosing (P less than 0.044) and for the average number of opsonized sheep erythrocytes (SRBC) ingested per phagocyte (P less than 0.045). A seasonal interaction was noted for average number of SRBC ingested per phagocyte: the relative difference in macrophage responses between obese and lean groups became significantly more pronounced during winter and spring months (P less than 0.080). Macrophages from obese pigs also exhibited higher phagocytic activities at C3-mediated phagocytosis than did cells from lean pigs, but these differences were significant only for average number of SRBC ingested per phagocyte (P less than 0.080). Exogenous linolenic acid was added to selected cultures undergoing Fc (gamma)-mediated phagocytosis. Addition of the fatty acid frequently caused enhanced phagocytosis. Macrophages from obese pigs were stimulated by fatty acid treatment more frequently than cells from lean pigs (P less than 0.05). Relatively greater enhancement was also seen in cells from obese pigs, when compared with those from lean swine (P less than 0.025). These results suggest that genetically transferred factors are of primary importance in alveolar macrophage phagocytic responses and that linolenic acid can induce increased phagocytic activity by porcine alveolar macrophages in vitro.

Lack of correlation between in vitro and in vivo activation of complement in mice by infective Trichinella spiralis larvae.

Very little is known about the role played by complement in vivo during Trichinella spiralis infections, although previous reports indicate that it binds readily to the surfaces of muscle stages of the parasite in vitro. In order to study the binding of complement to muscle-stage larvae in vivo, larvae were recovered from BALB-c inbred, NFR/N inbred, and Swiss white outbred mice from 20 to 95 days postinfection. The presence of C3 was examined by direct immunofluorescence and leucocyte- and erythrocyte-adherence tests. Complement was found on a few larvae from the outbred strain and only rarely on larvae from the 2 inbred strains. Histological sections prepared from inbred strains and used in immunofluorescence tests to study in situ complement activation and binding were negative. Larvae from all 3 mouse strains bound complement 100% of the time when it was added to the worms in vitro. The results indicate that extrapolation from in vitro to in vivo activation and binding of complement to T. spiralis larvae may not be valid.

Responses of NFR/N inbred mice to very low-dose infections with Ascaris suum.

Mice were evaluated for immunological responses and resistance to challenge infections after single infections. When given infections simultaneously with thiabendazole, larval migration to the liver and lungs was blocked but not when mice were given infections only. Enlargement of Peyer's patches was observed after infection followed by increased numbers of IgA-containing cells in the lamina propria of the intestines and increased levels of hepatobiliary IgA. Ig-containing cells were variable in the spleens during the early phase of infection. The observed changes quickly returned to normal control levels and did not change throughout the rest of the experiment. Serum Ig levels did not change dramatically. Challenge with high doses of eggs indicated that mice given single very low-dose infections became highly resistant.

Complement activation, phagocytosis, tumor growth and parasitic infection after magnesium supplementation in diet of mice.

Very little study has been devoted to Mg2+ supplementation in the diet and the effects produced upon biological functions. In the present study, mice were given supplemental amounts of MgCl2 or MgSO4 in the feed ration, while the following were examined: activation of serum complement, phagocytosis, growth of tumor transplants and infections with Trichinella spiralis. Increased complement activation, increased phagocytosis, decreased tumor growth and decreased severity of parasitic infection were observed in mice fed Mg2+ supplement. It is not yet certain how Mg2+ functions in order to produce an enhancement of resistance in the susceptible naive animal.

Effects of Trichinella spiralis infections upon bone marrow stem cells in BALB/c mice.

Trichinella spiralis infections provoke a variety of responses in the host, some of which involve stem cell proliferation and myeloid cell maturation, increases in the mast cell precursor cell populations, and maturation and eosinopoiesis. Very little is known about the influence of T. spiralis upon bone marrow stem cells and splenic colony formation. In the present communication we report that T. spiralis infection in mice stimulates the generation of colony-forming units in the spleen (CFU-S). Passive transfer of bone marrow cells from uninfected BALB/c mice to X-irradiated (650 R) T. spiralis-infected recipients resulted in a significant increase of CFU-S at 14 and 24 days postinfection. Passive transfer of bone marrow cells from T. spiralis-infected mice to X-irradiated uninfected mice also resulted in increased numbers of CFU-S in the donor mice at 24 days postinfection. These findings strongly suggest that T. spiralis infection conditions the microenvironment in the spleen which stimulates CFU-S.

Enhanced luminol-dependent chemiluminescence of stimulated rat alveolar macrophages by pretreatment with alveolar lining material.

Previous reports indicate that the in vitro bactericidal activity of rat alveolar macrophages (AM) is dependent on the lipid fraction (ALM-L) of the alveolar lining material (ALM). The present study demonstrates that luminol-dependent chemiluminescence of stimulated rat AM is increased when rat AM are preincubated in the ALM or in the ALM-L. Evidence is presented that oxidation of the unsaturated lipids is responsible for the increase. In addition to pretreatment with the ALM, cells were also pretreated in commercial preparations of several lipids found to be present in the ALM. Preincubation in these lipids produced a significant increase in the luminol-dependent chemiluminescence response. However, when a saturated lipid, dipalmitoyl phosphatidylcholine, was used no increase was found. Pretreatment in ALM did not increase the nitro blue tetrazolium dye reduction by the AM, nor was the phagocytosis of latex beads by the AM altered by the addition of the ALM.

Immune response of poults following intranasal inoculation with Artvax vaccine and a formalin-inactivated Bordetella avium bacterin.

Poults 3 weeks and older developed temporary tracheal resistance to intranasal challenge following inoculation of either Artvax vaccine or formalin-inactivated Bordetella avium bacterin by the intranasal and eyedrop routes. Resistance usually persisted for 3-4 weeks after B. avium challenge. However, with constant exposure to infected controls, the vaccinated birds eventually developed tracheal infection. Day-old poults did not respond to either the Artvax or the bacterin and were completely susceptible to challenge. Two-week-old poults responded to some degree, but poults 3 weeks old and older responded best. Poults inoculated with bacterin by aerosol or by drinking water did not respond as well as those inoculated by the intranasal and eyedrop routes. When poults were given a single subcutaneous injection at 3 weeks of age and challenged 2 weeks later, three of five resisted infection for 18 days.

Enteral and parenteral responses in mice after primary infection with Trichinella spiralis (Nematoda).

Enteral and enteral-parenteral infections were produced with T. spiralis in albino, Swiss Webster, outbred mice. Primary enteral infections abbreviated with thiabendazole stimulated inflammatory changes in Peyer's patches and the lamina propria of the small intestine of mice. These changes were accompanied by increased IgA in the intestinal luminal wash. Primary enteral-parenteral infections similarly stimulated the gut, and, in addition, the spleen. Splenic stimulation resulted in production of IgG1, and IgG2 antibodies specific for T. spiralis L3.

Generation of chemotactic factor for granulocytes and monocytes from serum by fractions of Brucella abortus.

Several fractions isolated from Brucella abortus were examined for their ability to generate chemotactic factor from normal serum. Phenol phase lipopolysaccharides exhibited activity equivalent to that obtained with E. Coli lipopolysaccharide. A carbohydrate-rich aqueous methanol fraction was inhibitory at high concentrations, but a non-dialysable component of this fraction contained a potent stimulator of chemotactic activity. Protein-rich fractions from both strain 19 and strain 2308 were inactive. Preheating the serum at 56 degrees for 30 min prevented generation of chemotactic activity by the various fractions, suggesting a role for serum complement. No chemotactic activity was produced by Brucella fractions in C5-deficient DBA/2J mouse serum.

Characterization of macrophage functions in mice infected with Brucella abortus.

Macrophage spreading, surface receptor density/avidity, phagocytosis, random migration, chemotactic responsiveness, and serum lysozyme were examined during the course of infection (up to 60 days) of mice with Brucella abortus strain 19. Markedly enhanced in vitro spreading activity was observed throughout the period of study. The density/avidity of cell surface immunoglobulin G Fc receptors was increased for up to 60 days postinfection. Internalization of sheep erythrocytes via C3 receptors was significantly enhanced. Random locomotion and chemotactic responsiveness to lymphocyte-derived chemotactic factor and N-formyl-L-methionyl-L-leucyl-L-phenylalanine were markedly stimulated. Serum lysozyme was also elevated in infected animals. These changes indicated significant and prolonged enhancement of macrophage activity during Brucella infection. These findings are discussed in relation to previous reports describing macrophage activation by Brucella.

Detection of cell surface immunoglobulin on leucocytes by agglutination.

The detection of immunoglobulin (Ig) on murine peritoneal cell (PC) surfaces by an agglutination test is described. Addition of anti-mouse IgG (amIgG) to a suspension of PC results in agglutination of the cells. Trypsin or pronase treatment of the cells abrogated agglutination upon addition of amIgG. Incubation of washed murine PC with porcine IgG (pIgG) for 30 minutes resulted in agglutination of the cells upon addition of anti-porcine IgG (apIgG) to the cell suspension. This suggests that the heterologous pIgG is also able to bind to the murine cell surface. The implications of these findings are discussed and compared with respect to the agglutination test described herein and other techniques for detection of cytophilic antibody.

The involvement of sugars and Mg++ in the attachment of phagocytic cells to Ascaris suum juveniles.

In vitro adherence of washed peritoneal exudate cells (PECs) from mice to Ascaris suum juveniles was inhibited by D-glucosamine and D-galactosamine. Other carbohydrates tested had no apparent effect on adherence after incubation for 3 hr at any of the concentrations tested. Furthermore, attachment of PECs to A. suum juveniles was completely inhibited by the addition of ethylenediaminetetraacetate to the medium, but magnesium ethylene glycol bis(trichloroacetate) had no effect on adherence. The results suggest that receptors for glucosamine-like or galactosamine-like molecules in conjunction with Mg++ are involved in the attachment of pECs to A. suum juveniles in the absence of antibody and complement. Adherence mediated by carbohydrated and divalent cations may be involved in early nonspecific mechanisms of resistance against A. suum because the reaction did not depend on the presence of antibody and/or complement for attachment.

The isolation, long-term cultivation and characterization of bovine peripheral blood monocytes.

Bovine peripheral blood monocytes were isolated from buffy coats of ACD-anticoagulated whole blood. Cells cultivated on plastic surfaces for 20 h were judged to be 95% monocytes based on nonspecific esterase-1 staining, uptake of latex particles and surface receptor characteristics. Bovine monocytes were maintained up to 80 days in vitro in Dulbecco's modified Eagle medium with 15% horse serum and 15% foetal bovine serum. Several morphological and physiological features of bovine monocytes were examined during the course of culture. Cell size and cytoplasmic spreading, granulation and vacuolization increased progressively. Multinucleated giant cells predominated during the latter stages of in vitro culture. A high percentage of bovine monocytes possessed C3 and IgG Fc receptors, whereas IgM Fc and sheep erythrocyte receptors were not detected. Phagocytosis was mediated by the IgG receptor, but not by the C3 receptor. Peroxidase activity declined in a linear fashion, with cells essentially negative after 8 days of culture. Total cell protein and acid phosphatase increased during cultivation. Lysozyme activity was undetectable in both lysates and supernatants of bovine monocyte. These findings are consistent with the concept of maturation of mononuclear phagocytes. The procedures for isolation and cultivation described in this paper will provide methodology for detailed study of bovine mononuclear phagocytes.

Pasteurella multocida: antibody-mediated resistance to virulent challenge exposure in vaccinated turkeys.

Aspects of antibody-mediated resistance to Pasteurella multocida infection in vaccinated turkeys were investigated. Pasteurella immune serum obtained from vaccinated turkeys was shown to confer temporary protection to nonvaccinated turkey poults. Recipients given immune serum were free of clinical signs of disease for at least 8 days after IM challenge exposure with virulent P multocidae 1059. All turkeys given normal serum died within 36 hours of challenge exposure. Vaccinated bursectomized turkeys were more susceptible to IM challenge exposure than were vaccinated nonbursectomized turkeys. In two of three trials, mortality also occurred earlier in the bursectomized groups when compared with mortality in the control groups. The presence of specific antibody may be an important determinant in resistance to Pasteurella infection.