Prevalence of gestational diabetes and pregnancy outcomes in Nordland and Troms counties 2004­15. / Prevalens av diabetes blant gravide og svangerskapsutfall i Nordland og Troms 2004­15.

BACKGROUND: The aim was to investigate the prevalence of gestational diabetes and pregnancy outcomes in women with gestational diabetes in Nordland and Troms counties. MATERIAL AND METHOD: We included all 1 067 women with type 1 diabetes, type 2 diabetes and gestational diabetes among 34 915 births at four hospitals in Nordland and Troms counties from 2004 to 2015. Prevalence of diabetes was calculated based on ICD-10 codes in patient records for women with diabetes in Nordland and Troms counties, and compared with national prevalence figures from the Medical Birth Registry of Norway. Prevalence of pre-eclampsia, macrosomia (birth weight > 4 500 grams) and caesarian section was calculated for all women with diabetes and all those giving birth in the same region. RESULTS: Prevalence of type 1 diabetes and type 2 diabetes remained stable. Prevalence of gestational diabetes increased from 1.0 % to 4.0 % in Nordland and Troms counties and from 1.0 % to 3.8 % nationally. Prevalence of pre-eclampsia among all women with diabetes fell from 18.8 % in 2004-06 to 12.4 % in 2013-15. In women with diabetes, the prevalence of pre-eclampsia was 4.6 times higher, that of macrosomia was 3.5 times higher, and the proportion of caesarian sections was 2.3 times higher than in the background population. INTERPRETATION: Prevalence of gestational diabetes increased in Nordland and Troms counties, as it did nationally. Prevalence of pre-eclampsia among pregnant women with diabetes fell, but prevalence of pre-eclampsia, macrosomia and caesarean section was higher than in the background population.

Quantitative Proteomics of Gut-Derived Th1 and Th1/Th17 Clones Reveal the Presence of CD28+ NKG2D- Th1 Cytotoxic CD4+ T cells.

T-helper cells are differentiated from CD4+ T cells and are traditionally characterized by inflammatory or immunosuppressive responses in contrast to cytotoxic CD8+ T cells. Mass-spectrometry studies on T-helper cells are rare. In this study, we aimed to identify the proteomes of human Th1 and Th1/Th17 clones derived from intestinal biopsies of Crohn's disease patients and to identify differentially expressed proteins between the two phenotypes. Crohn's disease is an inflammatory bowel disease, with predominantly Th1- and Th17-mediated response where cells of the "mixed" phenotype Th1/Th17 have also been commonly found. High-resolution mass spectrometry was used for protein identification and quantitation. In total, we identified 7401 proteins from Th1 and Th1/Th17 clones, where 334 proteins were differentially expressed. Major differences were observed in cytotoxic proteins that were overrepresented in the Th1 clones. The findings were validated by flow cytometry analyses using staining with anti-granzyme B and anti-perforin and by a degranulation assay, confirming higher cytotoxic features of Th1 compared with Th1/Th17 clones. By testing a larger panel of T-helper cell clones from seven different Crohn's disease patients, we concluded that only a subgroup of the Th1 cell clones had cytotoxic features, and these expressed the surface markers T-cell-specific surface glycoprotein CD28 and were negative for expression of natural killer group 2 member D.

Exploring Work-Related Causal Attributions of Common Mental Disorders.

PURPOSE: Common mental disorders (CMDs) are major causes of sickness absence and disability. Prevention requires knowledge of how individuals perceive causal mechanisms, and in this study we sought to examine work-related factors as causal attribution of CMDs. METHODS: A trial sample of n = 1,193, recruited because they struggled with work participation due to CMDs, answered an open-ended questionnaire item about what they believed were the most important causes of their CMDs. The population included participants at risk of sickness absence, and participants with reduced work participation due to sickness absence, disability or unemployment. We used thematic content analysis and categorized responses from 487 participants who reported work-related factors as causal attributions of their CMDs. Gender differences in work-related causal attributions were also examined. RESULTS: The participants attributed their CMDs to the following work-related factors; work stress, leadership, reduced work participation, job dissatisfaction, work conflict, social work environment, job insecurity and change, workplace bullying, and physical strain. Women tended to attribute CMDs to social factors at work. CONCLUSION: Findings from this study suggest several work-related risk factors for CMDs. Both factors at the workplace, and reduced work participation, were perceived by study participants as contributing causes of CMDs. Thus, there is a need to promote work participation whilst at the same time targeting aversive workplace factors. Further, our findings indicate that work-related factors may affect women and men differently. This illustrates that the association between work participation and CMDs is complex, and needs to be explored further.

Intracellular growth of Mycobacterium avium subspecies and global transcriptional responses in human macrophages after infection.

BACKGROUND: Mycobacterium avium subsp. avium (Maa) and M. avium subsp. hominissuis (Mah) are environmental mycobacteria and significant opportunistic pathogens. Mycobacterium avium infections in humans and pigs are mainly due to Mah. It is not known whether this is caused by a difference in virulence or difference in exposure to the two subspecies. The aim of the present study was to investigate the ability of the M. avium subspecies to replicate intracellularly and to characterise the gene expression program triggered by infection of human primary macrophages. RESULTS: All isolates were able to invade and persist within human macrophages. However, intracellular replication was only evident in cells infected with the two Maa isolates. Transcriptional responses to the isolates were characterized by upregulation of genes involved in apoptosis, immune- and inflammatory response, signal transduction and NF-kB signaling, cell proliferation and T-cell activation. Although similar pathways and networks were perturbed by the different isolates, the response to the Maa subspecies was exaggerated, and there was evidence of increased activation of type I and II interferon signaling pathways. CONCLUSION: Mycobacterium avium isolates of different genetic characteristics invaded monocytes and induced different degree of macrophage activation. Isolates of Maa were able to replicate intracellularly suggesting that differences in exposure, uptake or induction of adaptive immunity are more likely explanations for the difference in prevalence between M. avium subspecies.

Novel insights into transmission routes of Mycobacterium avium in pigs and possible implications for human health.

Mycobacterium avium infection is a severe condition in humans, whereas pigs are often subclinically infected. Pig carcasses represent a possible source of human infection. Faecal excretion of M. avium was recently demonstrated in experimentally infected pigs, along with detection of M. avium in apparently normal lymph nodes. The present study investigates faecal excretion in naturally infected herds and the presence of live mycobacteria in lymph nodes. Two pig herds (A and B), with a history of sporadically suspected M. avium infection were sampled. Herd B used peat, as opposed to Herd A. Samples from peat, sawdust, drinking water, faeces and lymph nodes were collected. Identification of mycobacteria was performed by 16S rDNA sequencing and PCR. Mycobacterium avium isolates were analysed by Multi-Locus Variable Number of Tandem repeat Analysis (MLVA). Mycobacterium avium subsp. hominissuis was detected in samples of faeces, peat and lymph nodes from Herd B, often with identical MLVA profiles. Additionally, other non-tuberculous mycobacteria (NTM) were found in the same material. The absence of macroscopic lymph node lesions in the presence of M. avium subsp. hominissuis was frequently demonstrated. In Herd A, only one NTM isolate, which proved not to be M. avium, was found. Faeces might facilitate transmission of M. avium subsp. hominissuis between pigs and maintain the infection pressure in herds. The low incidence of macroscopic lesions together with the massive presence of M. avium subsp. hominissuis in lymph nodes from pigs kept on peat raises questions related to animal husbandry, food safety and human health.

Selection of vaccine-candidate peptides from Mycobacterium avium subsp. paratuberculosis by in silico prediction, in vitro T-cell line proliferation, and in vivo immunogenicity.

Mycobacterium avium subspecies paratuberculosis (MAP) is a global concern in modern livestock production worldwide. The available vaccines against paratuberculosis do not offer optimal protection and interfere with the diagnosis of bovine tuberculosis. The aim of this study was to identify immunogenic MAP-specific peptides that do not interfere with the diagnosis of bovine tuberculosis. Initially, 119 peptides were selected by either (1) identifying unique MAP peptides that were predicted to bind to bovine major histocompatibility complex class II (MHC-predicted peptides) or (2) selecting hydrophobic peptides unique to MAP within proteins previously shown to be immunogenic (hydrophobic peptides). Subsequent testing of peptide-specific CD4+ T-cell lines from MAP-infected, adult goats vaccinated with peptides in cationic liposome adjuvant pointed to 23 peptides as being most immunogenic. These peptides were included in a second vaccine trial where three groups of eight healthy goat kids were vaccinated with 14 MHC-predicted peptides, nine hydrophobic peptides, or no peptides in o/w emulsion adjuvant. The majority of the MHC-predicted (93%) and hydrophobic peptides (67%) induced interferon-gamma (IFN-γ) responses in at least one animal. Similarly, 86% of the MHC-predicted and 89% of the hydrophobic peptides induced antibody responses in at least one goat. The immunization of eight healthy heifers with all 119 peptides formulated in emulsion adjuvant identified more peptides as immunogenic, as peptide specific IFN-γ and antibody responses in at least one heifer was found toward 84% and 24% of the peptides, respectively. No peptide-induced reactivity was found with commercial ELISAs for detecting antibodies against Mycobacterium bovis or MAP or when performing tuberculin skin testing for bovine tuberculosis. The vaccinated animals experienced adverse reactions at the injection site; thus, it is recommend that future studies make improvements to the vaccine formulation. In conclusion, immunogenic MAP-specific peptides that appeared promising for use in a vaccine against paratuberculosis without interfering with surveillance and trade tests for bovine tuberculosis were identified by in silico analysis and ex vivo generation of CD4+ T-cell lines and validated by the immunization of goats and cattle. Future studies should test different peptide combinations in challenge trials to determine their protective effect and identify the most MHC-promiscuous vaccine candidates.

Increased frequency of intestinal CD4+ T cells reactive with mycobacteria in patients with Crohn's disease.

OBJECTIVE: The aim of this study was to assess the frequency of mycobacteria and Escherichia coli reactive T cells in intestinal biopsies from patients with Crohn's disease (CD) and ulcerative colitis (UC). MATERIALS AND METHODS: The biopsies were obtained by colonoscopy from adult patients with active CD (n = 5) and active UC (n = 4). The number of CD4+ T cell clones expanded and screened from each patient varied from 383 to 3972 giving a total of 16639 individual clones. The T cell clones were tested for responses to Mycobacterium avium subspecies paratuberculosis (MAP) and E. coli. The cytokine profile of 42 individual T cell clones from four CD patients was assessed. RESULTS: The frequency of mycobacteria reactive T cell clones in CD patients ranged from 0.17 to 1.63% and was higher (p = 0.038) than the frequency of E. coli reactive T cells ranging from 0 to 0.18%. No or very low numbers of mycobacteria reactive clones were detected in three UC patients while the fourth UC patient had a frequency similar to what was observed in CD patients. The frequencies of E. coli reactive T cell clones in UC patients ranged from 0 to 0.52%. T cell clones (n = 42) from CD patients all produced IL-17 and/or IFN-γ. Several clones were also able to produce IL-10. CONCLUSIONS: The high frequency of intestinal tissue resident T cells reactive to mycobacteria suggests that an adaptive immune response have taken place and argues that these bacteria may contribute to the chronic inflammation in CD.

First-line treatment of patients with disseminated poorly differentiated neuroendocrine carcinomas with carboplatin, etoposide, and vincristine: a single institution experience.

UNLABELLED: Poorly differentiated neuroendocrine carcinomas (PDECs) represent highly malignant tumors with an immense tendency to metastasize and with a poor prognosis. The treatment consists of palliative chemotherapy and corresponds to the treatment of extensive stage small cell lung cancer. MATERIAL AND METHODS: We present the patient characteristics and treatment results of 31 consecutive, chemonaïve patients with PDECs treated with carboplatin, etoposide, and vincristine. RESULTS: The response rate was 52%, the disease control rate 77%, and the median overall survival 15.3 months. The one-year survival rate was 55%, and the two-year survival rate was 19%. The median progression free survival (PFS) time was 6.6 months. Survival rates did not correlate with the Ki-67 proliferation index. The treatment was well tolerated. CONCLUSION: Treatment results with carboplatin, etoposide, and vincristine in chemonaïve patients with PDECs are comparable to those in patients with SCLC. The prognosis is however poor.

A comparative study of Mycobacterium avium subsp. avium and Mycobacterium avium subsp. hominissuis in experimentally infected pigs.

BACKGROUND: Mycobacterium avium subsp. avium (Maa) and Mycobacterium avium subsp. hominissuis (Mah) are opportunistic pathogens that may infect several species, including humans and pigs. Mah is however more frequently isolated from pigs than Maa, and it is unclear if this is due to difference in virulence or in exposure to the two organisms. Clinical isolates of each subspecies were administered perorally to ten domestic pigs, respectively. The animals were sacrificed at six and 12 weeks after inoculation. At necropsy, macroscopic lesions were recorded, and tissue samples were collected for mycobacterial culture, IS1245 real time PCR and histopathological examination. Culturing was also performed on faecal samples collected at necropsy. RESULTS: Macroscopic and histopathological lesions were detected in pigs infected with each subspecies, and bacterial growth and histopathological changes were demonstrated, also in samples from organs without gross pathological lesions. Six weeks after inoculation, live Mah was detected in faeces, as opposed to Maa. The presence of live mycobacteria was also more pronounced in Mah infected tonsils. In comparison, the Maa isolate appeared to have a higher ability of intracellular replication in porcine macrophages compared to the Mah isolate. CONCLUSIONS: The study shows that both subspecies were able to infect pigs. Additionally, the more extensive shedding of Mah might cause pig-to-pig transmission and contribute to the higher incidence of infection caused by this subspecies.

Temozolomide as second or third line treatment of patients with neuroendocrine carcinomas.

BACKGROUND: Knowledge of the clinical efficacy in recurrent neuroendocrine carcinomas is sparse. Treatment with temozolomide alone or in combination with capecitabine and bevacizumab has recently shown promising results. PATIENTS AND METHODS: Analysis of consecutive patients with neuroendocrine carcinomas (Ki-67 proliferation index >20%) and performance status 0-2 treated with temozolomide 200 mg/sqm orally days 1-5 every 28 days after at least one previous platin-containing chemotherapy regimen. RESULTS: Twenty-eight eligible patients received a median of 3 courses. Sixteen patients were evaluable for response: Six achieved stable disease and ten progressed. The median survival for the 28 patients was 3.5 months. Survival in patients with tumors of pancreatic origin (n = 7) was 7.0 months versus 2.9 months in non-pancreatic origin (n = 21). Patients in PS 0-1 (n = 22) had a median survival of 4.5 months versus 1.1 months in patients in PS 2 (n = 6). Ki-67 index ≥ 50% was associated with a significantly shorter median survival than Ki-67 index <50% (2.7 months versus 10.9 months). The treatment was well tolerated. CONCLUSION: Temozolomide monotherapy has limited effect in treatment of recurrent neuroendocrine carcinomas. Second line treatment with temozolomide in combination with other compounds should be further investigated in patients in good performance with Ki-67 index <50%.

Assessment of mental health trajectories before and after myocardial infarction, atrial fibrillation or stroke: analysis of a cohort study in Tromsø, Norway (Tromsø Study, 1994-2016).

OBJECTIVES: The increased survival rate of cardiovascular disease (CVD) implies a higher proportion of individuals who live with CVD. Using data from the Tromsø Study, we aimed to investigate mental health symptom trajectories before and after myocardial infarction, atrial fibrillation or stroke in a general population and to explore factors that contribute to the association. DESIGN: Cohort study. SETTING: Sample drawn from inhabitants of the municipality of Tromsø, Norway, who participated in the Tromsø Study (1994-2016). PARTICIPANTS: A total of 18 719 participants (52.3% women) were included, and of these 2098 (32.9% women) were diagnosed with myocardial infarction, 1896 (41.9% women) with atrial fibrillation and 1263 (42.9% women) with stroke. PRIMARY OUTCOME MEASURES: Mental health symptoms were assessed using the Hopkins Symptom Checklist-10 and the Conor Mental Health Index. RESULTS: The participants who were diagnosed with either myocardial infarction or stroke had a significant monotonous increase in mental health symptoms before myocardial infarction (p=0.029) and stroke (p=0.029) that intensified at the time of diagnosis. After the event, the study found a higher prevalence of mental health symptoms with a decline in symptom levels over time for myocardial infarction (p<0.001) and stroke (p=0.004), but not for atrial fibrillation (before: p=0.180, after: p=0.410). The risk of elevated mental health symptoms with myocardial infarction, atrial fibrillation and stroke was associated with sex (p<0.001), age (p<0.01), physical activity (p<0.001), diabetes (p<0.05) and other comorbidities (p<0.001). CONCLUSION: The study indicates that mental health problems among individuals with myocardial infarction, atrial fibrillation and stroke may have started to develop several years before the cardiovascular event and suggests that successful CVD rehabilitation may need to consider previous life factors. Future research is recommended to examine whether health promotion measures in a general population also create mental health resilience after a CVD event.

Biofilm formation by Mycobacterium avium isolates originating from humans, swine and birds.

BACKGROUND: Mycobacterium avium includes the subspecies avium, silvaticum, paratuberculosis and hominissuis, and M. avium subspecies has been isolated from various environments all over the world including from biofilms in water distribution systems. The aim of this study was to examine isolates of M. avium subsp. avium and M. avium subsp. hominissuis of different origin for biofilm formation and to look for correlations between biofilm formation and RFLP-types, and to standardise the method to test for biofilm formation. In order to determine the best screening method, a panel of 14 isolates of M. avium subsp. avium and M. avium subsp. hominissuis, were tested for their ability to form biofilm in microtiter plates under different conditions. Subsequently, 83 additional isolates from humans, swine and birds were tested for biofilm formation. The isolates were tested for the presence of selected genes involved in the synthesis of glycopeptidolipids (GPLs) in the cell wall of M. avium, which is believed to be important for biofilm formation. Colony morphology and hsp65 sequvar were also determined. RESULTS: Nine isolates from swine produced biofilm. There was a significant higher frequency of porcine isolates forming biofilm compared to human isolates. All isolates were previously characterised by IS1311- and IS1245-RFLP typing. The ability to form biofilm did not correlate with the RFLP-type, hsp65 sequevar, colony morphology or the presence of gene sequences related to GPL synthesis. CONCLUSION: The observed differences in biofilm forming abilities between porcine and human isolates raises questions regarding the importance of biofilm formation for infectious potential. The optimised method worked well for screening of multiple isolates.

Diffusion blotting for rapid production of multiple identical imprints from sodium dodecyl sulfate polyacrylamide gel electrophoresis on a solid support.

A very simple and fast method for diffusion blotting of proteins from precast SDS-PAGE gels on a solid plastic support was developed. Diffusion blotting for 3 min gave a quantitative transfer of 10% compared with 1-h electroblotting. For each subsequent blot from the same gel a doubling of transfer time is necessary to obtain the same amount of protein onto each blot. The relative transfer of low and high molecular weight components was similar in diffusion and electroblotting. However, both methods do give a higher total transfer of the low molecular weight proteins compared with the large proteins. The greatest advantage of diffusion blotting is that several blots can be made from each lane, thus enabling testing of multiple antisera on virtually identical blots. The gel remains on the plastic support, which prevents it from stretching or shrinking. This ensures identical blots and facilitates more reliable molecular weight determination. Furthermore, the proteins remaining in the gel can be stained with Coomassie Brilliant Blue or other methods for exact and easy comparison with the developed blots. These advantages make diffusion blotting the method of choice when quantitative protein transfer is not required.

Three-dimensional endoanal ultrasound assessment of the anal sphincters during rest and squeeze.

BACKGROUND: Current ultrasound assessment of the anal sphincter is based on measurements during rest. However, active constriction plays a role in maintaining continence. Here we assess female anal dimensions during rest and squeeze. METHODS: Thirty women were recruited for a cross-sectional endoanal ultrasound study after written consent according to an ethically approved protocol: nine 0-gravida, 10 with normal vaginal delivery, and 11 with complicated vaginal delivery (babies >4,500 g, operative vaginal delivery or perineal rupture). Endoanal three-dimensional (3D)-ultrasound volume was obtained during rest and squeeze. Length of anal canal and volume of the external and internal sphincters were determined. RESULTS: In the 0-gravida group, the mean anal canal at rest was 3.28 cm (SD: +/-0.63) compared with 2.30 (+/-0.77) in those who had given birth (p =0.002). Correspondingly, the volume of the external sphincter was 7.61 cm(3) (+/-2.63) versus 4.80 (+/-2.02) (p =0.004), and for the internal sphincter 2.63 (+/-1.18) versus 2.68 (+/-1.30) (p =0.98). There were no differences between rest and squeeze within the 0-gravida, but after a traumatic vaginal delivery the internal sphincter was smaller during squeeze (p =0.01), and the overlap between external and internal sphincter was 0.76 cm (+/-0.41), insignificantly shorter (p =0.09) than in the 0-gravida group at 1.21 (+/-0.62). CONCLUSIONS: Women with vaginal delivery had a shorter anal canal and smaller external sphincter than 0-gravida. Active squeeze had no effect on the dimensions of the sphincter apart from a reduction of the internal sphincter in those who had undergone a complicated delivery, possibly due to a dislodging upwards during squeeze.

Three-dimensional endoanal ultrasound assessment of the anal sphincters: reproducibility.

OBJECTIVE: Volume measurement of the anal sphincter can be a future method for assessing volume loss, muscle atrophy or laceration. Three-dimensional (3D) endoanal ultrasound is a technique for assessing the volume of the anal sphincters, but the reproducibility of the method is scarcely known. DESIGN: Cross-sectional, repeated measurements. SAMPLE: Twenty women were recruited for the study after written consent according to an ethically approved protocol, nine 0-gravida and 11 with traumatic vaginal deliveries. METHOD: Endoanal 3D-ultrasound volume was obtained during rest and squeeze. The length of the anal canal and the volume of the external and internal sphincters were determined by two observers. Observer 1 repeated the measurements three times for all 20 women, and observer 2 for the nine 0-gravida, and intra- and inter-observer variation was assessed. RESULTS: During rest, the anal length measurement had intra-class correlation coefficients of 0.91 for observer 1 and 0.85 for observer 2. The limits of agreement for inter-observer measurement were (-0.81 to 1.61) measured in centimeters. For the external anal sphincter volume, the intra-class correlation coefficients and the limits of agreement were correspondingly: 0.89, 0.78 and (-7.29 to 6.03) measured in cm(3), and for the internal anal sphincter volume: 0.85, 0.69 and (-1.72 to 2.95). The variation in identifying the external anal sphincter could rise to a corresponding 30% error in volume measurement. CONCLUSION: Although intra-class correlation coefficients showed good reproducibility for endoanal ultrasound measurements, the limits of agreement were less reassuring with sizeable variation in the volume assessment, probably due to uncertainty in landmark identification.

New probes used for IS1245 and IS1311 restriction fragment length polymorphism of Mycobacterium avium subsp. avium and Mycobacterium avium subsp. hominissuis isolates of human and animal origin in Norway.

BACKGROUND: Mycobacterium avium is an environmental mycobacterium that can be divided into the subspecies avium, hominissuis, paratuberculosis and silvaticum. Some M. avium subspecies are opportunistic pathogens for animals and humans. They are ubiquitous in nature and can be isolated from natural sources of water, soil, plants and bedding material. Isolates of M. avium originating from humans (n = 37), pigs (n = 51) and wild birds (n = 10) in Norway were examined by IS1245 and IS1311 RFLP using new and specific probes and for the presence of IS901 and ISMpa1 by PCR. Analysis and generation of a dendrogram were performed with the software BioNumerics. RESULTS: IS1311 RFLP provided clear results that were easy to interpret, while IS1245 RFLP generated more complex patterns with a higher discriminatory power. The combination of the two methods gave additional discrimination between isolates. All avian isolates except one were M. avium subsp. avium with two copies of IS1311 and one copy of IS1245, while the isolates of human and porcine origin belonged to M. avium subsp.hominissuis. The isolates from human patients were distributed randomly among the clusters of porcine isolates. There were few identical isolates. However, one isolate from a human patient was identical to a porcine isolate. Regional differences were detected among the porcine isolates, while there was no clustering of human isolates according to type of clinical symptoms or geographical location of the patient's home addresses. CONCLUSION: The results demonstrate that a wide range of M. avium subsp.hominissuis are present in pigs and humans in Norway, and that some of these isolates are very similar. It remains to be determined whether humans are infected from pigs or if they are infected from common environmental sources.

Natural killer cells act as early responders in an experimental infection with Neospora caninum in calves.

The intracellular protozoan parasite Neospora caninum is a cause of abortion and congenital disease in cattle worldwide. We have previously shown that natural killer (NK) cells produce IFN-gamma in response to N. caninum tachyzoites in vitro. This study aimed to investigate the role of NK cells and other cellular immune responses in an experimental N. caninum infection model in calves. Phenotyping of peripheral blood lymphocytes showed a drop in the percentage of NK cells at days 4-6 after i.v. inoculation, followed by an increase in the percentage of both NK cells and CD8+ T cells which peaked at days 11-15. A whole blood flow cytometric assay showed that CD4+ T cells were the major IFN-gamma producing cells, but in the early stages of the infection both NK cells and CD8+ T cells contributed to IFN-gamma production. We also compared the ability of two different N. caninum antigen preparations--sonicated soluble antigens and intact heat-inactivated parasites--to induce proliferation and IFN-gamma production in various cell types. Heat-inactivated tachyzoites induced a 3.7 times greater increase in the number of IFN-gamma producing NK cells compared with sonicated soluble antigens. This indicated the presence of some NK cell-stimulating antigens in the intact tachyzoite that were absent from the sonicated soluble antigens. The heat-inactivated whole tachyzoites also inhibited gammadelta T cell proliferation while the soluble antigens from N. caninum did not. We believe this is the first time NK cells have been demonstrated to be early responders in N. caninum infection in calves.