The 43 monoclonal antibody raised against feline T cells was found to react with a single-chain glycoprotein of Mr 72,000 that is present on most thymocytes, 60% of lymph node cells, 20% of splenocytes, and 45% of blood mononuclear cells. All CD4+ and CD8+ T cells were found to express the 43-reactive determinant, as did a small subpopulation of CD4-/CD8-/IgM- lymphocytes in the periphery. The 43-reactive determinant was not detected on B cells, macrophages, or other types of blood cells. The 43 antigen was phosphorylated in resting and activated T cells. Its expression was upregulated by stimulation with phorbol myristate acetate and with phytohemagglutinin. When added to concanavalin A-stimulated T-cell cultures in low concentrations, the 43 antibody was found to augment mitogenesis. The data indicate that this antibody may identify a CD5 homologue on feline T cells.

Seventy-five pigs from 4 facilities were examined for Salmonella choleraesuis by use of bacteriologic culture of feces, blood, WBC (buffy coat), mononuclear leukocytes, and neutrophils. The organism was isolated from 0 of 75 fecal samples, compared with isolation from 39 of 75 purified neutrophil preparations. Of the pigs that did not have Salmonella isolated from feces or blood, but had S choleraesuis isolated from neutrophils, 6 were further examined. These pigs from 2 groups again had culture performed at least 3 successive times to test for repeatability and to determine optimal number of neutrophils required for Salmonella isolation. These same pigs were euthanatized and necropsied. Nineteen tissue specimens from each pig were obtained for culture, but S choleraesuis was isolated only from neutrophil samples. Results indicate that neutrophils may contribute to the carrier state in pigs and should be cultured when attempting to identify S choleraesuis carrier swine.

A slot blot hybridization technique was applied detection of bluetongue virus (BTV) in blood mononuclear cells (BMNC) obtained from cattle with experimentally induced infection. This technique lacked sensitivity to detect the viral nucleic acid directly in clinical specimens. When aliquots of mononuclear cells from these cattle were cultivated in vitro for 10 days to amplify virus titer, only 33.3% of the samples collected during viremia gave a positive signal in the slot blot hybridization format. By contrast results for 34.3% of noncultured and 63.3% of cultured mononuclear cell samples collected during viremia were positive by immunofluorescence. The average number of infected cells, as detected by immunofluorescence in the noncultured mononuclear cell samples, was 1 to 5/300,000, and was usually > 10/300,000 in the cultured cell samples. Virus was isolated from all postinoculation blood samples obtained from 4 heifers that were seronegative at the time of inoculation, but was not isolated from any of the preinoculation samples, or from any of the postinoculation samples obtained from 2 heifers that were seropositive at the time of inoculation. When virus isolation was attempted from separated mononuclear cells in 2 heifers, 43.7% of the noncultured and 87.5% of the cultured samples had positive results.

Postoperative abdominal fluid changes were compared in 2 groups of horses; those undergoing double small-colon resection and anastomosis (n = 10) and those undergoing exploratory celiotomy alone (n = 5). Peritoneal fluid was collected before surgery and on postoperative days 1, 3, 5, and 7. Total and differential nucleated cell counts, RBC numbers, and total protein and fibrinogen concentrations were evaluated. In both groups, all values were significantly higher than normal on the first postoperative day (after small-colon resection and anastomoses, WBC = 130,350 +/- 23,310 cells/microliter, RBC 7,389,000 +/- 6,234,000 cells/microliter, total protein = 3.63 +/- 0.16 g/dl; after exploratory celiotomy alone, WBC = 166,620 +/- 34,340 cells/microliter, RBC = 295,000 +/- 86,070 cells/microliter, total protein 4.38 +/- 0.54 g/dl). The number of total peritoneal nucleated cells and RBC significantly decreased after the first postoperative day, whereas total protein and fibrinogen concentrations, percent neutrophils, and percent mononuclear cells remained unchanged. None of the values had returned to normal by postoperative day 7 (after small-colon resection and anastomoses, WBC = 45,600 +/- 8,765 cells/microliter, RBC = 95,390 +/- 53,380 cells/microliter, total protein = 4.39 +/- 0.23 g/dl; after exploratory celiotomy alone, WBC = 43,340 +/- 7,746 cells/microliter, RBC = 12,860 +/- 11,790 cells/microliter, total protein = 3.92 +/- 2.20 g/dl.) The resection and anastomosis group had a significantly lower total protein concentration on the first postoperative day and a significantly higher mean total RBC count over the entire 7-day postoperative evaluation than did horses that underwent celiotomy alone. Other values in the 2 groups of horses did not differ significantly. As a result, there was insufficient evidence to conclude that resection and anastomosis of the small colon in healthy horses causes a different inflammatory response than does manipulation of the intestine alone.

Porcine blood mononuclear cells (BMC) were exposed to prepartum concentration of estrogen in gilts before acquisition (in vivo), and their subsequent reactivity (in vitro) was explored. In a cross-over experimental designed study, 6 ovariectomized gilts were injected once with 3.75 mg of estradiol-17beta benzoate in arachidic oil or with arachidic oil only during 2 experiments. The ability of their BMC to proliferate in response to stimulation with phytohemagglutinin, concanavalin A, and pokeweed mitogen was assayed in cultures of blood and in cultures of purified BMC. After 2 days of mitogen stimulation, activity of accessible interleukin 2 was quantified in supernatants obtained from cultures of purified BMC and supernatants of blood cultures stimulated with pokeweed mitogen. Also, production of immunoglobulins by purified BMC in response to polyclonal stimuli was measured. Three days after treatment with estradiol, the proliferative response was suppressed in blood cultures stimulated with concanavalin A (P < 0.05) and phytohemagglutinin (P < 0.07). Effects of estradiol treatment were not found in any of the assays performed with purified BMC. We, therefore, assumed that in vivo exposure to estradiol can affect the function of porcine BMC; however, this was only evident when the in vitro assays were performed on blood cultures.

Concanavalin A (conA) blast proliferation as a quantitative measure of lymphoblast proliferative capacity by blood mononuclear cell supernatants was measured in cattle naturally infected with Mycobacterium paratuberculosis and in healthy control cattle. Blast cell proliferation was significantly reduced in infected animals, compared with control cattle when blood mononuclear cells were stimulated with conA. Proliferation was significantly greater than media control when M bovis purified protein derivative and johnin were used to stimulate cells from the infected group. After sensitizing control and affected cattle with M paratuberculosis bacterin (live M bovis and keyhole limpet hemocyanin in Freund's incomplete adjuvant), infected animals had no difference in blast cell proliferative capacity with the mycobacterial antigens and cona stimulation, whereas healthy animals had significantly increased blast proliferation in response to all the sensitizing antigens. The blast cell proliferative capacity in infected animals with keyhole limpet hemocyanin stimulation was increased significantly after sensitization; however, it remained significantly less than that in the sensitized control group. These data indicate that cattle naturally infected with M paratuberculosis probably produce suboptimal interleukin-2 (IL-2) activity in response to a potent IL-2 inducer (conA) and fail to optimize IL-2 activity when sensitized with a potent immunogen (keyhole limpet hemocyanin).

The lipoxygenase metabolites of arachidonic acid have an important role in lymphocyte activation. We used a specific 5-lipoxygenase inhibitor, A-63162, to examine the role of 5-lipoxygenase (5-LO) in equine blood mononuclear cell (BMC) proliferation and leukotriene B4 (LTB4) synthesis after stimulation with mitogen (phytohemagglutinin, PHA) or calcium ionophore (A23187). The A-63162 inhibited PHA-induced equine BMC proliferation and, at the same concentration, also inhibited A23187-induced LTB4 synthesis. The presence of exogenous interleukin 2 (IL-2) or the cyclooxygenase inhibitor indomethacin, failed to reverse the immunosuppression caused by A-63162. Further, we found that A-63162, at the concentration that inhibited BMC proliferation and LTB4 synthesis, had no effect on BMC viability. The addition of the specific protein kinase C inhibitor, H-7, did not inhibit A23187-induced LTB4 synthesis. Results indicate that 5-lipoxygenase metabolites may have an important role in equine lymphocyte activation and that protein kinase C has no role in regulating LTB4 production after A23187 stimulation.