Elevated serum IgA associated with immunoproliferative enteropathy of Basenji dogs: lack of evidence for alpha heavy-chain disease or enhanced intestinal IgA secretion.

Immunoglobulin isotypes in serum and intestinal secretions of Basenji dogs with chronic diarrhea, asymptomatic Basenji dogs, and healthy control dogs were quantitated and their molecular sizes characterized to detect alpha-chain, gamma-chain, or mu-chain fragments. Quantitation of immunoglobulin isotypes in serum showed that affected Basenjis have significantly elevated serum IgA values as compared to asymptomatic Basenjis and normal control dogs. However, IgA concentrations in intestinal wash fluids were not significantly different for the three groups. Immunoelectrophoresis (IEP) and polyacrylamide gel electrophoresis (PAGE) demonstrated that virtually all IgA was in the dimeric form. Using IEP and immunoselection, we were unable to detect evidence for the presence of alpha-chain or other heavy-(H)-chain fragments. Hyperimmune serum obtained from rabbits immunized with serum or a globulin fraction of affected Basenjis also failed to detect H-chain fragments. The results of this study indicate that immunoproliferative enteropathy of Basenjis resembles closely the nonsecretory form of human immunoproliferative small intestinal disease (IPSID).

A method for the accurate determination of the specificity of monoclonal antibodies reactive with porcine immunoglobulins.

Monoclonal antibodies against porcine IgG were produced by fusion and characterized. The supernatants of microtiter wells containing fusion hybrids were first screened with an ELISA using semi-purified porcine IgG as antigen. Hybrids reactive in ELISA were cloned by limiting dilution. Further characterization of the specificity of the monoclonal antibodies was done by a combination of two methods: SDS-PAGE electroimmunoblotting and convection blotting of immunoelectrophoretic patterns (IEP-immunoblotting). Using these techniques, we identified monoclonal antibodies specific for porcine Ig gamma chains.

Effective in vivo depletion of T cell subpopulations and loss of memory cells in cattle using mouse monoclonal antibodies.

Conditions were established to obtain depletion of T lymphocyte subsets in lymphoid tissues of calves by injection of mouse monoclonal antibodies to T cell antigens. Adverse reactions were avoided by injecting small quantities of antibody, until target cells had disappeared from blood. Two different mechanisms appeared to be responsible for elimination of the target cells. Rapid depletion of T cells was associated with complement-binding antibody isotypes (IgG2a, IgM), suggesting a complement-mediated mechanism. Clearance of T cells after several days was observed with a non complement-binding isotype (IgG1), suggesting phagocytosis or induction of apoptosis as possible mechanisms. Clearance of the cells in peripheral blood and spleen was obtained with 10-20 mg of anti-CD4 or anti-CD8, but almost ten times as much was needed to obtain depletion of the cells in lymph nodes and Peyer's patches. Depletion lasted for 12 days for CD4 T cells and 3 weeks for CD8 T cells. Successful and lasting depletion (at least 2 weeks) was also obtained with other T cell reagents, such as anti-CD2 and anti-WC1 (gamma/delta T cells). Although B lymphocytes could be removed by a complement-binding antibody, complete depletion of these cells only lasted for a few hours, probably because B cells regenerate faster than T cells. T cell function was severely inhibited when CD4+ T cells were depleted. Stimulation of T cells with foot and mouth disease viral antigen (FMDV) in vaccinated calves was non-existent after depletion. Even 2 months after restoration of normal CD4 T cell levels in blood, activity to FMDV was low. This suggested that the depleted T cells were replaced by naive cells.

Hemolytic complement in specific-pathogen-free chickens: influence of age and sex.

Six groups of specific-pathogen-free (SPF) chickens of various ages were tested for hemolytic complement (C) activity with a radial hemolytic diffusion technique. The chickens tested were 2, 6, 7, and 8 weeks old. Chickens 2 weeks old were found to have little hemolytic activity compared with chickens 6 to 8 weeks old. Mean titers were similar in the older chickens. No significant differences were found in C titers between males and females, unlike reports for mice.

Infectious bursal disease viral infections. II. The relationship of age, complement levels, virus-neutralizing antibody, clotting, and lesions.

Experimental infection with infectious bursal disease virus (IBDV) reduced the complement (C) titer in 8-week-old chickens on days 3, 5, and 7 postinfection. Since the C titer was much lower in normal 2-week-old chickens than in normal 8-week-old chickens it could not be determined whether there was a reduction in titer during the infection process. Virus-neutralizing antibody rose rapidly following infection in both 2- and 8-week-old chickens. Hyper-immune serum given during infection in an attempt to produce immune complexes did not increase disease severity in either 2- or 6-week-old susceptible chickens.

Infectious bursal disease viral infections. I. Complement and virus-neutralizing antibody response following infection of susceptible chickens.

Complement (C) titers were decreased at 3 days postinfection, and virus-neutralizing (VN) antibody was detectable at 3 or 4 days postinfection in chickens with infectious bursal disease virus (IBDV). Clotting times were prolonged in all groups tested during the acute phase of the disease. Mortality appeared to be associated with the severity of decrease in C titer. The results suggest that the mortality and many of the clinical signs seen with infectious bursal disease are associated with: 1) a depletion in circulating levels of hemolytic C from the formation of immune complexes at sites of viral replication; and/or 2) a depletion in some clotting factor which results in hemorrhage.

Nucleotide sequence and vaccinia expression of the nucleoprotein of a highly virulent, neurotropic strain of Newcastle disease virus.

The nucleoprotein (NP) of Newcastle disease virus (NDV) was selected to study the relative importance of an internal structural protein in the avian immune response. The NP gene of the virulent, neurotropic NDV Texas GB (TGB) strain was cloned and sequenced. Nucleotide sequence data for the NP gene allowed comparison of the deduced amino acid sequences for the NP genes of NDV-TGB and the avirulent duck isolate NDV-D26. These comparisons demonstrated an 89% nucleotide sequence homology and a 97% homology between the deduced amino acid sequences. The NDV-TGB NP expressed in recombinant vaccinia virus (rVAC) was electrophoretically and immunologically identical to the wild-type NDV-TGB. Although inoculation of chickens with the recombinant vaccinia virus expressing the NDV NP gene elicited anti-NDV antibodies in higher titers than in birds inoculated with live LaSota NDV, this strong anti-NDV response did not protect against lethal challenge with NDV-TGB.

Monoclonal gammopathy associated with naturally occurring canine ehrlichiosis.

Clinical, hematologic, and immunologic findings for 14 dogs with Ehrlichia canis monoclonal gammopathy were studied retrospectively. Epistaxis, anemia, thrombocytopenia, hypoalbuminemia, hypergammaglobulinemia, and proteinuria were documented in the majority of these dogs. The serum protein electrophoresis pattern was characterized by a distinct narrow-base monoclonal spike, by a broad-base monoclonal spike, or by a monoclonal spike superimposed on a polyclonal gammopathy. The monoclonal spike disappeared following tetracycline treatment for ehrlichiosis. The long-term prognosis following treatment was generally good. The diagnostic features of monoclonal gammopathy due to myeloma were compared with those of E. canis monoclonal gammopathy. Owing to numerous similarities in clinical, hematologic, and immunologic findings, we conclude that an E. canis antibody titer should be determined in all dogs in which a diagnosis of benign monoclonal gammopathy is contemplated or definitive evidence of myeloma, leukemia, or macroglobulinemia is lacking.

Gastric acid secretion in Basenji dogs with immunoproliferative enteropathy.

Gastric acid secretion was studied in 13 Basenji dogs with immunoproliferative enteropathy. Considerable variation in the severity of gastritis and enteritis existed among dogs. Basenji dogs were categorized into two groups on the basis of postmortem gastric and intestinal histology (group I, gastritis and enteritis; group II, only enteritis). Pentagastrin-induced gastric acid secretory capacity was increased (P less than 0.002) in group II dogs as compared to healthy Beagle controls. Gastric acid secretory capacity of Basenji dogs with gastritis and enteritis (group I) was not different from that observed in control dogs. Basal serum gastrin concentrations and secretin-stimulated serum gastrin concentrations of either group of Basenji dogs did not differ from controls. On the basis of symptomatology, Basenji dogs with diarrhea had significantly increased basal and postsecretin stimulation gastrin concentrations (P = 0.01) when compared with asymptomatic Basenji or healthy control dogs. These findings support a potential role for altered gastric acid secretory capacity in the pathogenesis of immunoproliferative enteropathy of Basenji dogs. Results of the secretin stimulation studies support previous pathologic studies that failed to detect gastrin-secreting tumors. Incorporated into this investigation was a trial to determine whether the combination of oxymorphone and acepromazine could be used for acid secretory studies. Compared to pentobarbital, which has been frequently used for acid secretory studies in a research setting, the drug combination resulted in increased gastric fluid volumes, a comparative increase in acid secretion, and a rapid uneventful recovery. We conclude that the combination of oxymorphone and acepromazine provides an acceptable means of restraint in dogs undergoing acid secretory studies.

Preparation of monospecific antiserums against porcine immunoglobulins, using agarose-linked immunosorbents.

Immunoglobulins IgG, IgA, and IgM were isolated from porcine serum and milk, and antiserums against the 3 immunoglobulin classes were prepared. Monospecificity of the antiserums for the gamma-, alpha-, and mu-chains was obtained by absorbing them in agarose-linked immunosorbent columns. These immunosorbents were prepared by linking IgG or IgA-IgM to CNBr-activated agarose. Contaminating anti-alpha2-macroglobulin antibodies in the anti-IgA and anti-IgM serums were removed with agarose-linked fetal globulins.

Isolation of porcine secretory immunoglobulin A by affinity chromatography and determination of its component chains.

Porcine secretory immunoglobulin A (SIgA) was isolated in a single step from porcine milk whey by affinity chromatography, using antiporcine alpha-chain specific antibody linked to CNBr-activated agarose. The isolated SIgA contained no other proteins detectable by immunodiffusion of immunoelectrophoresis. After reduction and alkylation with dithiothreitol and iodoacetamide, the SIgA was chromatographed on gel equilibrated with 6.0 M urea and 1.0 M propionic acid. Polyacrylamide gel electrohoresis of the fractions eluted revealed the presence of light chain, alpha-chain secretory component, and J-chain.

Scanning electron microscopy of experimentally induced pyelonephritis in the rat.

Scanning electron microscopy was used to observe epithelial and inflammatory changes in kidneys of rats during Corynebacterium renale-induced experimental ascending pyelonephritis. Bacteria were not observed adhering to pelvic epithelium, although there was evidence of cell sloughing. Bacteria was observed in the interstitium of the renal medulla. Bacteria, when present in the tubular lumen, were associated with discontinuities in cell membranes. Phagocytic cells appeared in the interstitium and phagocytosis was evident in the renal medulla.

Appearance of immunoglobulin classes and complement (C3) during Corynebacterium renale-induced experimental pyelonephritis in the rat.

The local appearance of various immunoglobulin (Ig) isotypes in the urinary tract during ascending pyelonephritis was studied in rats experimentally infected with Corynebacterium renale. The indirect fluorescent antibody assay was used to detect IgG, IgM, IgA, IgE, and C3 on C renale present in the urine of the experimental animals. Corynebacterium renale coated with IgM and IgG antibodies was found beginning on the 4th day after induced infection, with IgG being the more abundant isotype. Coating with IgA occurred as early as the 4th day, but was less dense than coating with IgG. The presence of C3 on C renale was concurrent with IgM and IgG coating. A significant quantity of IgE could not be identified on antibody-coated C renale. Thus, IgG is the major component of the humoral immune response in this model of ascending pyelonephritis. The IgM early during infection and IgA later during infection seem not to be a major component of the immune response in this model.

Rhinitis, pneumonia, and defective neutrophil function in the Doberman pinscher.

Eight closely related Doberman Pinschers with chronic rhinitis and pneumonia had normal or increased numbers of structurally normal leukocytes. Serum concentrations of immunoglobulins and complement were above or within normal ranges. Lymphocyte transformation indices for 3 mitogens were normal in 7 of the 8 dogs; the remaining dog had low values for all mitogens. Neutrophils phagocytized bacteria normally, but had impaired bactericidal ability. The bactericidal defect may have been related to the inability of neutrophils to generate normal numbers of oxygen radicals after stimulation, as determined by decreased ability of neutrophils to reduce nitroblue tetrazolium and to produce superoxide following opsonized zymosan stimulation. These observations, plus finding chronic inflammatory disease in the lungs of one dog, indicated that the disease may have some similarity to chronic granulomatous disease or to complement receptor deficiency in man.