Effects of dexamethasone treatment on IL-1 receptor mRNA levels in vivo.

Using semiquantitative reverse transcriptasepolymerase chain reaction and Northern analysis, we observed in vivo up-regulation of interleukin-1 (IL-1) RI and IL-1RII mRNA levels in peripheral blood mononuclear cells (PBMCs) and neutrophils (PMNs) from Holstein cattle injected with dexamethasone (0.04 mg/kg). Baseline levels of IL-1RI mRNA were greater than IL-1RII mRNA levels in PBMCs and PMNs before dexamethasone treatment. This is in contrast with the previously reported predominance of IL-1RII in unstimulated human PMNs. IL-1RII mRNA was strongly induced in both bovine PBMCs and PMNs at 24 h and returned to baseline levels by 72 h, after dexamethasone injection. Conversely, the greatest increase in IL-1RI mRNA in PBMCs and PMNs was not detected until 72 h after dexamethasone injection. These data provide evidence for sequential in vivo up-regulation of first IL-1RII mRNA and later IL-1RI mRNA by dexamethasone that is consistent with the anti-inflammatory activity of glucocorticoids.

Regulation of bovine interleukin-1 receptors.

Interleukin-1 is a key player in inflammation and the immune response. The interleukin-1 family consists of three ligands (IL-1 alpha, IL-1 beta, and the IL-1 receptor antagonist) and two receptors (IL-1RI and IL-1RII). Previous studies suggest a dynamic relationship among these receptors and ligands that regulates the magnitude and extent of IL-1 mediated activities. Our laboratory has cloned and sequenced the bovine type I and II interleukin-1 receptors, and has begun to investigate their regulation in bovine leukocytes in vitro and in vivo. IL-1RI and IL-1RII mRNA levels were upregulated in vitro by various mediators, including dexamethasone, rBoIL-4, rBoGM-CSF, and rHuTNF alpha. Conversely, IL-1RI mRNA levels were down-regulated by IFN-gamma. An in vivo study indicated that IL-1RII mRNA levels increased earlier than IL-1RI mRNA levels in dexamethasone-treated cattle. These findings suggest that early upregulation of IL-1RII, which is a decoy receptor, may be part of the anti-inflammatory action of glucocorticoids. Our investigations suggest that anti-inflammatory agents increase expression of the biologically inactive IL-1RII, as compared with the biologically active IL-1RI, in bovine leukocytes.

Flow cytometric analysis of intracellular complexity and CD45 expression for use in rapid differentiation of leukocytes in bovine blood samples.

OBJECTIVE: To develop an efficient and reliable method that accurately differentiates bovine lymphocytes from monocytes in leukograms. SAMPLE POPULATION: Blood samples from 30 healthy cows and 1 calf with bovine leukocyte adhesion deficiency. PROCEDURE: Flow cytometric analysis of intracellular complexity and CD45 expression on bovine leukocytes was compared with results for conventional light microscopy methods. Verification of leukocyte subpopulations determined by intracellular complexity and CD45 expression was conducted, using 2-color phenotypic analysis with selected monoclonal antibodies. RESULTS: The CD45 and side-scatter properties of bovine leukocytes clearly differentiated cell types, including neutrophils, eosinophils, monocytes, and lymphocytes. CONCLUSIONS AND CLINICAL RELEVANCE: This is a rapid assay that is simple to use. More importantly, it is more accurate than the conventional method that involves the use of blood slides and light microscopy, because of the ability of the assay to readily distinguish bovine monocytes and lymphocytes. Rapid preparation of samples and short analysis times allow for efficient and reliable examination of a large number of samples, and the task of viewing slides by light microscopy is eliminated. The labor-savings benefit of this procedure is most apparent in research environments that require frequent processing of batches of blood samples.

Fecal shedding of coliform bacteria during the periparturient period in dairy cows.

OBJECTIVE: To determine whether numbers of coliform bacteria in feces of dairy cattle changed during the periparturient period and whether fluctuations were associated with changes in dry-matter intake. ANIMALS: 12 healthy Holstein cows. PROCEDURE: Fecal samples were collected on a semi-regular basis (i.e., 3 to 7 times/wk) beginning 4 to 6 weeks before the anticipated parturition date and continuing through the third day (5 cows) or second week (7 cows) after parturition, and total numbers of fecal coliform bacteria were determined. Daily feed intake of 7 cows was monitored. RESULTS: For 11 cows, fecal coliform bacterial counts between 34 and 25 days prior to parturition were low and relatively constant (< 102 change in number of bacteria). Coliform bacteria were not detected in 4 to 8% of fecal samples from 10 cows. All cows had a 10(4) to 10(7) increase in number of colony forming units/g of feces near the time of parturition. Number of fecal coliform bacteria peaked within 7 days of parturition in 9 cows and within 12 days of parturition in 3. Number of fecal coliform bacteria was not correlated with feed intake. CONCLUSIONS AND CLINICAL RELEVANCE: Cows may have large increases in fecal coliform bacteria count during the periparturient period; however, periparturient cows do not continually shed high numbers of coliform bacteria, and coliform bacteria may not always be detectable by conventional culture methods. Changes in fecal coliform bacteria count did not correlate with changes in dry-matter intake.