Genes In Blood Leukocytes Research Articles

Gene Expression Analysis of Peripheral Cells for Subclassification of Pediatric Inflammatory Bowel Disease in Remission

ObjectiveIn current clinical practice, optimal treatment of inflammatory bowel disease (IBD) aims at the induction and maintenance of clinical remission. Clinical remission is apparent when laboratory markers of inflammation are normal and clinical symptoms are absent. However, sub-clinical inflammation can still be present. A detailed analysis of the immune status during this inactive state of disease may provide a useful tool to categorize patients with clinical remission into subsets with variable states of immune activation.DesignBy using Affymetrix GeneChips, we analysed RNA gene expression profiles of peripheral blood leukocytes from pediatric IBD patients in clinical remission and controls. We performed (un)supervised clustering analysis of IBD-associated genes and applied Ingenuity® pathway software to identify specific molecular profiles between patients.ResultsPediatric IBD patients with disease in clinical remission display heterogeneously distributed gene expression profiles that are significantly distinct from controls. We identified three clusters of IBD patients, each displaying specific expression profiles of IBD-associated genes.ConclusionThe expression of immune- and IBD-associated genes in peripheral blood leukocytes from pediatric IBD patients in clinical remission was different from healthy controls, indicating that sub-clinical immune mechanisms are still active during remission. As such, RNA profiling of peripheral blood may allow for non-invasive patient subclassification and new perspectives in treatment regimes of IBD patients in the future.

Two potential biomarkers identified in mesenchymal stem cells and leukocytes of patients with sporadic amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a fatal, neurodegenerative disorder caused by degeneration of motor neurons. The cause for most cases of ALS is multi-factorial,this enhances the need to characterize and isolate specific biomarkers found in biological samples from ALS patients. To this end we use human mesenchymal stem cells (hMSC) derived from the bone marrow of six ALS patients (ALS hMSC) and identified two genes, Cytoplasmic FMR Interacting Protein 2 (CyFIP2) and Retinoblastoma (Rb) Binding Protein 9 (RbBP9) with a significant decrease in post transcriptional A to I RNA editing compared to hMSC of healthy individuals. At the transcriptional level we show abnormal expression of these two genes in ALS hMSC by quantitative real time-PCR (qRT-PCR) and Western blot suggesting a problem in the regulation of these genes in ALS. To strengthen this view we tested by qRT-PCR the expression of these genes in peripheral blood leukocytes (PBL) isolated from blood samples of 17 ALS patients and found that CyFIP2 and RbBP9 levels of expression were significantly different compared to the levels of expression of these two genes in 19 normal PBL samples. Altogether we found two novel ALS potential biomarkers in non-neural tissues from ALS patients that may have direct diagnostic and therapeutic implications to the disease.

Two Potential Biomarkers Identified in Mesenchymal Stem Cells and Leukocytes of Patients with Sporadic Amyotrophic lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal, neurodegenerative disorder caused by degeneration of motor neurons. The cause for most cases of ALS is multi-factorial,this enhances the need to characterize and isolate specific biomarkers found in biological samples from ALS patients. To this end we use human mesenchymal stem cells (hMSC) derived from the bone marrow of six ALS patients (ALS hMSC) and identified two genes, Cytoplasmic FMR Interacting Protein 2 (CyFIP2) and Retinoblastoma (Rb) Binding Protein 9 (RbBP9) with a significant decrease in post transcriptional A to I RNA editing compared to hMSC of healthy individuals. At the transcriptional level we show abnormal expression of these two genes in ALS hMSC by quantitative real time-PCR (qRT-PCR) and Western blot suggesting a problem in the regulation of these genes in ALS. To strengthen this view we tested by qRT-PCR the expression of these genes in peripheral blood leukocytes (PBL) isolated from blood samples of 17 ALS patients and found that CyFIP2 and RbBP9 levels of expression were significantly different compared to the levels of expression of these two genes in 19 normal PBL samples. Altogether we found two novel ALS potential biomarkers in non-neural tissues from ALS patients that may have direct diagnostic and therapeutic implications to the disease.

Expression of NRF2 and NRF2-modulated genes in peripheral blood leukocytes of bladder cancer males

Nuclear factor (erythroid-derived 2)-like 2 (NRF2) is an oxidant-responsive transcription factor involved in induction of antioxidant genes. We assessed NRF2 and selected NRF2-modulated gene expression: glutathione S-transferase A1 and P1 (GSTA1 and GSTP1), mitochondrial superoxide dismutase (SOD2) in blood leukocytes of 51 bladder cancer patients and 90 control males. A significant up-regulation of SOD2 expression (P=0.002) was observed in leukocytes of patients. NRF2 expression was positively correlated with GSTP1 and with SOD2 mRNA level, both in patients and controls. These data suggest disturbances in SOD2 transcription in circulating blood leukocytes of males with bladder cancer. Moreover, concomitant constitutive expression of NRF2 and its target genes may suggest important role of NRF2 transcription factor in positive regulation of antioxidant genes, resulted in enhanced cytoprotection in human peripheral blood leukocytes.

Selection of reliable reference genes for quantitative real-time PCR in human T cells and neutrophils

BackgroundThe choice of reliable reference genes is a prerequisite for valid results when analyzing gene expression with real-time quantitative PCR (qPCR). This method is frequently applied to study gene expression patterns in immune cells, yet a thorough validation of potential reference genes is still lacking for most leukocyte subtypes and most models of their in vitro stimulation. In the current study, we evaluated the expression stability of common reference genes in two widely used cell culture models-anti-CD3/CD28 activated T cells and lipopolysaccharide stimulated neutrophils-as well as in unselected untreated leukocytes.ResultsThe mRNA expression of 17 (T cells), 7 (neutrophils) or 8 (unselected leukocytes) potential reference genes was quantified by reverse transcription qPCR, and a ranking of the preselected candidate genes according to their expression stability was calculated using the programs NormFinder, geNorm and BestKeeper. IPO8, RPL13A, TBP and SDHA were identified as suitable reference genes in T cells. TBP, ACTB and SDHA were stably expressed in neutrophils. TBP and SDHA were also the most stable genes in untreated total blood leukocytes. The critical impact of reference gene selection on the estimated target gene expression is demonstrated for IL-2 and FIH expression in T cells.ConclusionsThe study provides a shortlist of suitable reference genes for normalization of gene expression data in unstimulated and stimulated T cells, unstimulated and stimulated neutrophils and in unselected leukocytes.

Decreased expression of B cell related genes in leukocytes of women with Parkinson's disease

BackgroundParkinson's disease (PD) is a complex disorder caused by genetic, environmental and age-related factors, and it is more prevalent in men. We aimed to identify differentially expressed genes in peripheral blood leukocytes (PBLs) that might be involved in PD pathogenesis. Transcriptomes of 30 female PD-patients and 29 age- and sex-matched controls were profiled using GeneChip Human Exon 1.0 ST Arrays. Samples were from unrelated Ashkenazi individuals, non-carriers of LRRK2 G2019S or GBA founder mutations.ResultsDifferential expression was detected in 115 genes (206 exons), with over-representation of immune response annotations. Thirty genes were related to B cell functions, including the uniquely B cell-expressed IGHM and IGHD, the B cell surface molecules CD19, CD22 and CD79A, and the B cell gene regulator, PAX5. Quantitative-RT-PCR confirmation of these 6 genes in 79 individuals demonstrated decreased expression, mainly in women patients, independent of PD-pharmacotherapy status.ConclusionsOur results suggest that the down regulation of genes related to B cell activity reflect the involvement of these cells in PD in Ashkenazi individuals and represents a molecular aspect of gender-specificity in PD.

The expression of two novel orange-spotted grouper ( Epinephelus coioides) TNF genes in peripheral blood leukocytes, various organs, and fish larvae

The tumour necrosis factor (TNF) super-family is a group of important cytokines involved in inflammation, apoptosis, cell proliferation, and the general stimulation of the immune system. The TNF gene has been cloned in some bony fish; however, its counterparts are still unidentified in the majority of fish species. In this study, we cloned gTNF-1 and gTNF-2 from the orange-spotted grouper ( Epinephelus coioides), an economically important farmed fish. Both genes include 4 exons and 3 introns and encoded 253 and 241 amino acid proteins with a molecular weight of approximately 27 and 26 kDa, respectively. The identity of the putative amino acid sequences between gTNF-1 and gTNF-2 was only 38%. The positions of cysteine residues, a protease cleavage site, and a transmembrane domain sequence derived from gTNF-1 and gTNF-2 were similar to those in other fish and mammalian TNF-α. The mRNA expression levels of the 2 gTNF molecules were evaluated in unstimulated/stimulated peripheral blood leukocytes, various organs, and fish larvae. Following lipopolysaccharide (LPS) treatment, gTNF-2 was expressed at higher levels, was up-regulated more quickly, and was more sensitive to the immune response than gTNF-1. gTNF-1 was constitutively expressed in the thymus, brain, and spleen, but it was also expressed in the heart, head kidney, and trunk kidney after LPS stimulation. gTNF-2 was constitutively expressed in the thymus, head kidney, trunk kidney, spleen, and intestine; further, gTNF-2 was highly expressed in all organs post-LPS stimulation. Finally, the gTNF expression levels were evaluated at various developmental stages in grouper larvae. A higher variation of gTNF expression levels was observed in fish larvae from a contaminated hatchery. This study revealed the different expression patterns of gTNF-1 and gTNF-2. In addition, gTNF-2 was more sensitive to pathogens than gTNF-1; therefore, it may be an appropriate marker for pathogen invasion and the evaluation of the larval rearing environment.

Evaluation of Allelic Expression of Imprinted Genes in Adult Human Blood

BackgroundImprinted genes are expressed from only one allele in a parent-of-origin dependent manner. Loss of imprinted (LOI) expression can result in a variety of human disorders and is frequently reported in cancer. Biallelic expression of imprinted genes in adult blood has been suggested as a useful biomarker and is currently being investigated in colorectal cancer. In general, the expression profiles of imprinted genes are well characterised during human and mouse fetal development, but not in human adults.Methodology/Principal FindingsWe investigated quantitative expression of 36 imprinted genes in adult human peripheral blood leukocytes obtained from healthy individuals. Allelic expression was also investigated in B and T lymphocytes and myeloid cells. We found that 21 genes were essentially undetectable in adult blood. Only six genes were demonstrably monoallelic, and most importantly, we found that nine genes were either biallelic or showed variable expression in different individuals. Separated leukocyte populations showed the same expression patterns as whole blood. Differential methylation at each of the imprinting control loci analysed was maintained, including regions that contained biallelically expressed genes. This suggests in some cases methylation has become uncoupled from its role in regulating gene expression.Conclusions/SignificanceWe conclude that only a limited set of imprinted genes, including IGF2 and SNRPN, may be useful for LOI cancer biomarker studies. In addition, blood is not a good tissue to use for the discovery of new imprinted genes. Finally, lymphocyte DNA methylation status in the adult may not always be a reliable indicator of monoallelic gene expression.

Gene Expression Profiling of Apoptosis Regulators in Patients with Sepsis

Introduction: Sepsis is associated with a dysregulation of apoptosis in immune cells, which has been implicated in both immunosuppression and multiple organ failure. We describe the expression profiles of genes encoding key regulators of apoptosis in highly purified monocytes, granulocytes and CD4+ T lymphocytes. Methods: Sixteen patients with sepsis were recruited from the intensive care unit and were compared with 24 healthy controls. RNA was isolated from highly purified monocyte, granulocyte and CD4+ T-lymphocyte populations. Gene expression profiles were determined using multiplex ligation-dependent probe amplification for the simultaneous detection of 30 pro- and anti-apoptotic target genes. Results: Relative to healthy controls, patients with sepsis showed increased transcription of both pro- and anti-apoptotic genes in peripheral blood leukocytes. Specific monocyte, granulocyte and CD4+ T-lymphocyte mRNA profiles were identified. Anti-apoptotic profiles were found in monocytes and granulocytes, while CD4+ T lymphocytes displayed a foremost pro-apoptotic mRNA profile. Conclusions: These data indicate that in patients with sepsis, the alterations in apoptosis of circulating leukocytes occur in a cell-specific manner.

Non-invasive diagnosis of acute rejection in kidney transplants with delayed graft function

Delayed graft function (DGF) often occurs in kidney transplants from deceased donors. We wanted to provide studies giving more accurate non-invasive tests for acute rejection (AR). Using real-time PCR, we examined the expression of cytolytic molecules such as perforin, granzyme B, and fas-ligand along with serpin proteinase inhibitor-9. We also measured the expression of FOXP3, a characteristic gene of T-regulatory cells known to be involved in AR. These studies were conducted on peripheral blood monocytes, urinary cells, and 48 surveillance kidney biopsies taken from a total of 35 patients with DGF. Of these patients, 20 had a histopathological diagnosis of AR, whereas other 28 had characteristics of acute tubular necrosis (ATN). Expression of cytolytic and apoptotic-associated genes in the biopsy tissue, peripheral blood leukocytes, and urinary cells was significantly higher in patients with AR than that in patients with ATN. Diagnostic parameters associated with FOXP3 gene expression were most accurate in peripheral blood leukocytes and urine cells with sensitivity, specificity, positive and negative predictive values, and accuracy between 94 and 100%. Our study shows that quantification of selected genes in peripheral blood leukocytes and urinary cells from renal transplant patients with DGF may provide a useful and accurate non-invasive diagnosis of AR.

Acute Effects of Haemodialysis on Pro-/Anti- Apoptotic Genes in Peripheral Blood Leukocytes

Several studies have implicated a remarkable dysfunctional apoptotic state and/or response in ESRD patients. Previously published studies are controversial with respect to acute effects of haemodialysis (HD) treatment on up- or downregulation of apoptotic genes. Twenty-eight chronic HD patients were haemodialysed for 4 hours with a 4008 dialyser using high-flux membranes. For subgroup analysis, patients were separated into a low (up to 0.5 mg/dl) and a high (0.5 to 5.0 mg/dl) CRP group. Blood was drawn prior to HD and 240 min after initiation of HD. Acute changes of transcript levels encoding pro- or anti-apoptotic genes were analyzed in RNA immediately isolated from blood leukocytes using quantitative real-time PCR. In the present study, we detected a significant elevation of the death receptor CD95/Fas (induction factor (IF) 1.55 ± 0.16), the death receptor 5 (DR5) (IF 1.17 ± 0.08), and caspase 8 (IF 1.37 ± 0.14) gene expression during HD. mRNA levels of the respective ligands (CD95L, TRAIL), of the caspase 5 and anti-apoptotic Bcl-2 family members such as Bcl-2 and Bcl2l2 were slightly, but not significantly, increased after HD treatment. An additional anti-apoptotic molecule, BAG3, was found to be slightly, but significantly, induced after HD (IF 1.16 ± 0.07). In addition to being an activator of immune cells, CD40L has been shown to be strongly induced after HD treatment (IF 1.70 ± 0.20). Subgroup analysis revealed no significant differences between low vs. high CRP patient groups or diabetic vs. non-diabetic patients. These results indicate a marked influence of routine haemodialysis treatment on the transcription of pro- and anti-apoptotic molecules and the involvement of the extrinsic pathway for apoptosis through the activation of death receptors and the initiator caspase 8. Furthermore, following dialysis, lymphocytes seem to be activated by CD40L, which represents an early T-cell activation marker.

Differential Gene Expression Induced by Exposure of Captive Mink to Fuel Oil: A Model for the Sea Otter

Free-ranging sea otters are subject to hydrocarbon exposure from a variety of sources, both natural and anthropogenic. Effects of direct exposure to unrefined crude oil, such as that associated with the Exxon Valdez oil spill, are readily apparent. However, the impact of subtle but pathophysiologically relevant concentrations of crude oil on sea otters is difficult to assess. The present study was directed at developing a model for assessing the impact of low concentrations of fuel oil on sea otters. Quantitative PCR was used to identify differential gene expression in American mink that were exposed to low concentrations of bunker C fuel oil. A total of 23 genes, representing 10 different physiological systems, were analyzed for perturbation. Six genes with immunological relevance were differentially expressed in oil-fed mink. Interleukin-18 (IL-18), IL-10, inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2), and complement cytolysis inhibitor (CLI) were down-regulated while IL-2 was up-regulated. Expression of two additional genes was affected; heat shock protein 70 (HSP70) was up-regulated and thyroid hormone receptor (THR) was down-regulated. While the significance of each perturbation is not immediately evident, we identified differential expression of genes that would be consistent with the presence of immune system-modifying and endocrine-disrupting compounds in fuel oil. Application of this approach to identify effects of petroleum contamination on sea otters should be possible following expansion of this mink model to identify a greater number of affected genes in peripheral blood leukocytes.

High-Throughput mRNA Profiling Characterizes the Expression of Inflammatory Molecules in Sepsis Caused by Burkholderia pseudomallei

Sepsis is characterized by an uncontrolled inflammatory response to invading microorganisms. We describe the inflammatory mRNA profiles in whole-blood leukocytes, monocytes, and granulocytes using a multigene system for 35 inflammatory markers that included pro- and anti-inflammatory cytokines, chemokines, and signal transduction molecules in a case-control study with 34 patients with sepsis caused by the gram-negative bacterium Burkholderia pseudomallei (the pathogen causing melioidosis) and 32 healthy volunteers. Relative to healthy controls, patients with sepsis showed increased transcription of a whole array of inflammatory genes in peripheral blood leukocytes, granulocytes, and monocytes. Specific monocyte and granulocyte mRNA profiles were identified. Strong correlations were found between inflammatory mRNA expression levels in monocytes and clinical outcome. These data underline the notion that circulating leukocytes are an important source for inflammatory mediators in patients with gram-negative sepsis. Gene profiling such as was done here provides an excellent tool to obtain insight into the extent of inflammation activation in patients with severe infection.

Regulation of Interferon-Stimulated Genes in Peripheral Blood Leukocytes in Pregnant and Bred, Nonpregnant Dairy Cows

In ruminants, pregnancy results in up-regulation of a large number of IFN-stimulated genes (ISG) in the uterus. Recently, one of these genes was also shown to increase in peripheral blood leukocytes (PBL) during early pregnancy in sheep. Our working hypothesis is that conceptus signaling activates maternal gene expression in PBL in dairy cattle. The objectives of this study were to characterize ISG expression in PBL from pregnant (n=20) and bred, nonpregnant (n=30) dairy cows. Steady-state levels of mRNA for Mx1, Mx2, β2-microglobulin, ISG-15, IFN regulatory factor-1, and IFN regulatory factor-2 were quantified. Holstein cows were synchronized to estrus and artificially inseminated (d 0). Blood samples were collected (coccygeal venipuncture) on d 0 and 16, 18, and 20 d after insemination for progesterone analysis and PBL isolation. Pregnancy was confirmed by transrectal ultrasonography at approximately 40 d after breeding. A status×day interaction was detected for Mx1, Mx2, and ISG-15 gene expression. When analyzed within day, levels of mRNA for ISG-15 and Mx1 were greater in pregnant compared with bred, nonpregnant cows on d 18 and 20, respectively. Expression of the Mx2 gene increased in the pregnant group compared with bred, nonpregnant cows on d 16, 18, and 20 after insemination. β2-Microglobulin, IFN regulatory factor-1, and IFN regulatory factor-2 were not different between groups. The results clearly indicated that components of the innate immune response are activated in PBL during the period of pregnancy recognition and early embryo signaling. The physiological implications of these changes on maternal immune function are as yet unknown; however, they do provide a unique opportunity to identify bred, nonpregnant, cows 18 d after insemination in dairy cattle.

Cold stress equally enhances in vivo pro-inflammatory cytokine gene expression in chicken lines divergently selected for antibody responses

The effects of cold stress, immunization and genetic selection on the expression of mRNA for cytokine genes in poultry have not been completely elucidated. Therefore, in the present experiment, using real-time quantitative RT-PCR, we evaluated the effect of cold stress and immunization with complete Freund's adjuvant (CFA) on expression of mRNA for pro-inflammatory (interleukin-1beta [IL-1β], IL-6, IL-12β), Th 1 (IFN-γ and IL-2), and Th 2 (IL-4 and IL-10) cytokine genes in peripheral blood leukocytes (PBL) of chicken lines divergently selected for either high or low antibody responses. Irrespective of the duration, cold stress enhanced expression of mRNA for IL-1β, IL-6, IL-12β and IL-4 cytokine genes in both selection lines. These results indicate that cold stress stimulates both the innate and parts of the adaptive cellular immune system. Immunization with CFA resulted in higher expression of mRNA for pro-inflammatory cytokines and lower expression of mRNA for both Th 1 and Th 2 cytokines.

Expression analysis of psychological stress-associated genes in peripheral blood leukocytes

In this study, we have developed a microarray including 1467 cDNAs that were selected to specifically measure stress response in peripheral blood leukocytes. Venous blood was collected from 10 graduate students 2 h before and 2 or 24 h after an open presentation for their Ph.D. The mRNA levels in leukocytes were compared with those prepared 4 weeks before the presentation. Hierarchical cluster showed that distinct groups of genes uniformly changed their expression values in response to the stress. Bayesian t test identified significantly up-regulated 49 genes and down-regulated 21 genes. Most of them are categorized into cytokines, cytokine receptors, growth- or apoptosis-related molecules, and heat shock proteins, suggesting that stressful life events trigger acute responses in leukocytes. Our results suggest that gene expression profile in peripheral blood leukocytes may be a potentially useful method for the assessment of complex stress responses.

Assessment of human stress and depression by DNA microarray analysis

Precise assessment of stress is an imminent issue to deal with stress-related social, medical and psychological problems. Psychological stress is known to stimulate the neuroendocrine, sympathetic nervous, and immune systems. By analyzing mRNA expression levels in leukocytes, which express receptors for hormones, neurotransmitters, growth factors, cytokines, and other stress related signals, levels of stress may be adequately measured. In a series of studies, our group has developed a cDNA microarray specifically designed to measure the mRNA levels of stress-related genes in peripheral blood leukocytes. This microarray enabled us to sensitively detect the response to psychological stress. In addition, our preliminary study suggests that the array could differentiate patients with depression from sex- and age-matched control subjects.

Influenza-Associated Encephalopathy and Febrile Convulsions

The transcription of cytokine genes in peripheral blood leukocytes (PBL) of 23 children (mean age 3.2 years) with influenza (mostly type A) complicated by encephalopathy (11 patients) or febrile convulsions (12 patients) was compared with systemic cytokine responses in 23 (mean age 5.0 years) with influenza but without neurologic complications, in a study at Nagoya University Graduate School of Medicine, Japan.

Systemic cytokine responses in patients with influenza-associated encephalopathy.

Influenza-associated encephalopathy, a severe neurologic complication of influenza, is being reported more frequently in Japan. We investigated the transcription of cytokine genes in peripheral blood leukocytes and compared patients with influenza and with encephalopathy or febrile convulsions and patients with influenza but without neurologic complications. A quantitative polymerase chain reaction (PCR) revealed that transcription of the interleukin (IL)-6, IL-10, and tumor necrosis factor-alpha genes was up-regulated to a greater extent in patients with encephalopathy than in those without neurologic complications. Plasma IL-6 levels also were higher in patients with encephalopathy, although the difference was marginal. Viral RNA in throat swabs was quantified using a real-time quantitative PCR. The virus load was similar among patients with encephalopathy or febrile convulsions or without neurologic complications. Furthermore, virus load was not correlated with either the transcription of cytokine genes or plasma cytokine concentrations. These results suggest that influenza-associated encephalopathy might be a consequence of systemic immune responses.

An Immunogenomics Approach to Understanding Periparturient Immunosuppression and Mastitis Susceptibility in Dairy Cows*

Studies comparing in vivo and in vitro functional capacities of leukocytes from non-parturient and periparturient dairy cows have provided substantial evidence that systemic and local mammary immune defenses are deficient around parturition. This evidence has lead to the reasonable hypothesis that immune deficiency underlies the heightened mastitis susceptibility of periparturient cows. Nutrition and vaccine studies substantiate this hypothesis, showing that dietary antioxidant supplementation and rigorous immunization regimes can bolster innate and humoral immunity to the point that mastitis severity and time for return to normal milk production are reduced. However, completely effective resolution of this significant production disease has not been achieved because so little is understood about its complex etiology. In particular, we possess almost no knowledge of how or why immune cells responding to parturient physiology end up with deficient functional capacities. Fluctuations in reproductive steroid hormones and chronic shifts in neuroendocrine hormones with roles in nutrient partitioning and appetite control may affect the expression of critical leukocyte genes in periparturient dairy cows. A thorough understanding of leukocyte biology during periparturition would seem a critical goal for future development of effective mastitis prevention strategies. Recently, our group has begun to use cDNA microarray technology to explore bovine leukocyte RNA for global gene expression changes occurring around parturition. We are working within the context of a hypothesis that the physiology of parturition negatively affects expression of critical genes in blood leukocytes. In the current study we initiated hypothesis testing using leukocyte RNA from a high producing Holstein cow collected at 14 days prepartum and 6 hours postpartum to interrogate a cDNA microarray spotted with > 700 cDNAs representing unique bovine leukocyte genes. This analysis revealed 18 genes with > or = 1.2-fold higher expression 14 days prepartum than 6 hours postpartum. BLASTN analysis of these genes revealed only one that can be considered a classical immune response gene. All other repressed genes were either unknown or putatively identified as encoding key proteins involved in normal growth and metabolism of cells. Given the critical roles of these repressed genes in normal cell functions, we may have identified good candidates to pursue with respect to periparturient immunosuppression and mastitis susceptibility.