Early changes in the phenotypic composition of lymphocytes in the bronchoalveolar lavage of pigs after aerogenic immunization with Pasteurella multocida aerosols

Immunohistochemical study of porcine lung lesions associated with Pasteurella multocida

Infectious bronchopneumonia is a widespread disease in modern commercial pig production and Pasteurella multocida is frequently associated with the lesions. To evaluate porcine lung lesions associated with P. multocida, populations of inflammatory cells were examined by immunohistochemistry in necrotic lung lesions from nine pigs and exudative lung lesions from eleven pigs. Lungs from five pigs served as controls. All cases were selected from naturally infected pigs using co-infection based criteria to make them as comparable as possible. The inflammatory cells demonstrated by immunohistochemistry were T-lymphocytes (CD3⁺, CD4⁺ and CD8⁺ subsets), B-lymphocytes, neutrophils, macrophages, and IgA⁺, IgM⁺ and IgG⁺ cells.

The results showed that (1) a significant increase in all inflammatory cells was found in lesions associated with P. multocida, (2) necrotic lesions had a larger number of CD3⁺ T-lymphocytes and IgA⁺ cells, and (3) cases with exudative lesions had a more CD8⁺ T-lymphocytes, B-lymphocytes, macrophages and neutrophils. No differences in the numbers of CD4⁺ T-lymphocytes, IgG⁺ and IgM⁺ positive cells were found between necrotic and exudative cases. The results show that P. multocida significantly alters the inflammatory response in the lung and that lesions associated with P. multocida display diverse inflammatory responses according to their distinct morphological pattern.

The expression of CD25, CD11b, SWC1, SWC7, MHC-II, and family of CD45 molecules can be used to characterize different stages of γδ T lymphocytes in pigs

The expression of selected molecules was chosen to study porcine γδ lymphocytes and their CD2/CD8 subsets in different lymphoid organs in vivo and in vitro. Results indicate that many γδ T cells can constitutively express CD25 and MHC-II and that the frequency of γδ T cells positive for CD25, CD11b, SWC1 and SWC7 can be increased by stimulation. A diversified TCRδ repertoire was found inside CD25(+), CD11b(+), SWC1(-) and CD45RA(-) cells. Ontogenetic studies revealed various age and/or colonization dependency for expression of all studied molecules except of SWC7. Findings generally indicate that CD25 represent an activation molecule that probably marks a functionally distinct subsets, expression of CD11b is perhaps connected to early functions of naive γδ T cells in the periphery, SWC1 is lineage specific marker, SWC7 may represent an activation molecule with intrinsic or transient expression, and the expression of CD45RA/RC most likely defines naive and terminally differentiated cells.

Rapidly progressive and lethal septicemia due to infection with Pasteurella multocida in an infant

We report a case of rapidly progressive pneumonia and meningoencephalitis in a 2-month-old breastfed infant. Culture of cerebrospinal fluid was positive for Pasteurella multocida. No bite or scratch injury as site of entrance could be detected clinically or at autopsy, therefore aerogenic transmission in droplets from a household pet must be considered. Infections with P. multocida have been frequently reported in infants and elderly people; however, rapidly progressive and lethal infections in infants have been described only rarely. These infections must be regarded as preventable through adequate measures of hygiene.

Blood cellular immune response in pigs immunized and challenged with Haemophilus parasuis

The cellular immune response to an experimental infection by Haemophilus parasuis, the etiological agent of Glässer's disease in pigs, was characterized studying changes in peripheral blood mononuclear cells (PBMC) in colostrum-deprived pigs. Five groups were studied, four of those were previously immunized with different formulations and the fifth was maintained as non-immunized control. All groups were challenged with 5 x 10(9) CFU of H. parasuis serotype 5. The non-commercial bacterin conferred a complete protection, while the OMP-vaccine and the exposure to a subletal dose of 10(5) CFU of H. parasuis protected only partially, and the recombinant Tbp B-vaccine induced no protection. PBMC were analyzed using monoclonal antibodies against porcine CD45(+), CD3(+), CD4(+), CD8alpha(+), CD25(+), CD4(+) naïve, alphaIgM(+) and SWC3(+) cells in single-colour fluorescence, and CD4(+)/CD8alpha(+) and CD8alpha(+)/CD8beta(+) combinations in two-colour fluorescence. The different groups showed no significant changes in PBMC subsets following vaccination, and only minor changes were encountered after challenge, consisting mainly of significant increases (P<0.05) in the relative proportions of monocytes and granulocytes (SWC3(+)) and B cells (alphaIgM(+)), as well as a significant reduction in CD3(+) cells (P<0.05). These changes were similar for the five groups compared, except for the significant increase of CD25(+) cells, which was only observed for the bacterin-vaccinated group. These results suggest an increase of trafficking of inflammatory cells and the onset of the adaptive antibody response against H. parasuis infection; in addition, the blood cellular response developed by the different groups was not relevant to protection.

Experimental Actinobacillus pleuropneumoniae infection in piglets with different types and levels of specific protection: Immunophenotypic analysis of lymphocyte subsets in the circulation and respiratory mucosal lymphoid tissue

Actinobacillus pleuropneumoniae (APP) infection in piglets results in severe and fatal fibrinous hemorrhagic necrotizing pneumoniae. The aim of our study was to analyze changes in lymphocyte subset distribution in peripheral blood, bronchoalveolar lavage fluid (BALF) and tracheobronchal lymph nodes (TLN) in non-immune piglets upon a challenge with a high dose of APP and to compare the quality of such changes in unprotected piglets with counterparts exhibiting specific immunity mediated by high titers of colostrum-derived APP-specific antibodies and/or a low dose APP infection in the early postnatal period. Challenge with APP resulted in a massive increase in CD8-negative gammadelta T-cells in parallel with a reduction in numbers of CD3-CD8low cells in BALF independent of the type and level of immunity and this seems to be a general phenomenon associated with experimental infection. An increase in B-lymphocyte numbers in TLN was another characteristic feature accompanying APP infection in all experimental groups. In piglets with colostrum-derived APP-specific antibodies, this was associated with higher relative numbers of IgM+CD2+ lymphocytes in TLN, while B-cells with the CD2- surface phenotype apparently expanded in the absence of passive humoral immunity.

Immunology of the porcine respiratory disease complex

PRDC is a multifactorial respiratory syndrome that includes several respiratory pathogens. As can be observed in this article, although the pathogenesis of some of the respiratory pathogens of pigs is fairly well defined, the host response and the immune response necessary to control the pathogen often remain unclear. As our ability to evaluate the porcine immune system and its ability to respond to disease improves, the knowledge of how each of these respiratory pathogens alter and evade the immune system will increase. The pathogens most commonly isolated from pigs with clinical signs of PRDC either infect the cells of the immune system or induce significant immunopathology. Thus, PRRSV and M. hyopneumoniae, the two most common pathogens associated with PRDC, alter the ability of the respiratory immune system to respond to their presence and the presence of other pathogens. By changing the respiratory immune system, these two common pathogens increase the susceptibility to the many other pathogens associated with PRDC. As we learn more about the pathogens of the respiratory system, their interactions with each other, and the mechanisms by which they modulate the immune system, our ability to develop effective control measures will improve.

Antibody reactions after aerogenous or subcutaneous immunization of pigs with Pasteurella multocida antigens

Depending upon the antigens used and the initial titres, subcutaneous immunization of weaner pigs by means of a temperature-sensitive mutant of live Pasteurella multocida (serovar A), resulted in a significant rise of the level of specific IgG antibody already present in blood serum, but not in lung lavage fluid, and a specific stimulation of lung clearance as compared to non-immunized controls. Aerogenous immunization of a total of 108 animals in 18 experiments did not influence serum antibody titres but produced a significant rise in lung antibodies and P. multocida clearance as compared to an identical number of controls. In all 12 immunization experiments using the live mutant, increased specific IgA antibodies and in seven out of 10 experiments, elevated IgG antibodies were measured. Only aerogenous immunization was found to be capable of reducing the severity of pneumonia induced by intrabronchial infection.

Studies of the influence of ochratoxin A on immune and defence reactions in weaners

Even in subtoxic amounts, the mycotoxin, ochratoxin A, produced immunomodulation in weaner pigs in a dose-dependent mode. In addition to increased counts of total leukocytes and neutrophils in the blood, reduced lymphocyte levels were observed. There was a striking increase in the counts of eosinophils and of apoptotic phagocytes. Functionally, there was a predominance of the production of reactive oxygen radicals in whole blood, reduced phagocytosis performance and reduced expression of a swine-specific surface marker (SWC1) on lymphocytes. In a few single experiments, clinical manifestations could be demonstrated. Lung clearance and the degree of severity of experimental pneumonia as well as cutaneous hypersensitization may be influenced by ochratoxin A.