Development and evaluation of an index assessing adherence to the Norwegian food-based dietary guidelines: the Norwegian Dietary Guideline Index (NDGI).

BACKGROUND: Monitoring adherence to the Norwegian food-based dietary guidelines (FBDGs) could provide valuable insight into current and future diet-related health risks. This study aimed to develop and evaluate an index measuring adherence to the Norwegian FBDGs to be used as a compact tool in nutrition surveillance suitable for inclusion in large public health surveys. METHODS: The Norwegian Dietary Guideline Index (NDGI) was designed to reflect adherence to the Norwegian FBDGs on a scale from 0-100, with a higher score indicating better adherence. Dietary intakes were assessed through 19 questions, reflecting 15 dietary components covered by the Norwegian FBDGs. The NDGI was applied and evaluated using nationally representative dietary data from the cross-sectional web-based Norwegian Public Health Survey which included 8,558 adults.​ RESULTS: The population-weighted NDGI score followed a nearly normal distribution with a mean of 65 (SD 11) and range 21-99. Mean scores varied with background factors known to be associated with adherence to a healthy diet; women scored higher than men (67 vs. 64) and the score increased with age, with higher educational attainment (high 69 vs. low 64) and with better self-perceived household economy (good 67 vs. restricted 62). The NDGI captured a variety of dietary patterns that contributed to a healthy diet consistent with the FBDGs. CONCLUSION: The NDGI serve as a compact tool to assess and monitor adherence to the Norwegian FBDGs, to identify target groups for interventions, and to inform priorities in public health policies.​ The tool is flexible to adjustments and may be adaptable to use in other countries or settings with similar dietary guidelines.

The influence of immigrant background and parental education on overweight and obesity in 8-year-old children in Norway.

BACKGROUND: Little is known about the prevalence of overweight/obesity and socio-economic position (SEP) in children with immigrant background in Scandinavia. The purpose of this study is to examine the prevalence of overweight/obesity by immigrant background among children in Norway and to explore the role of SEP in explaining differences in weight status. METHODS: Anthropometric data from 8,858 children (age 8.3 years) from the population-based Norwegian Childhood Growth Study were used. Information about immigrant background, country of origin, and parental education (used as an indicator of SEP) were provided by Statistics Norway. For children with immigrant background, regional background was determined based on country of origin. Prevalence ratios (PR) were estimated for overweight/obesity and weight-to-height-ratio (WHtR) ≥ 0.5 by immigration and regional background, using generalized estimating equation log-binominal models adjusting for sex, age, survey year (model 1), residential area, population density (model 2) and parental education (model 3). RESULTS: Children with immigrant background had a higher prevalence of overweight/obesity and WHtR ≥ 0.5 than non-immigrant background children. Adjusted for parental education, children with an immigrant background from Southern and Eastern Europe, Asia except South-Asia, and Africa had a higher prevalence of overweight/obesity [PR: 1.37 (95% confidence interval (CI): 1.10-1.72), 1.28 (1.05-1.57), 1.47 (1.13-1.91), respectively] than children with a non-immigrant background. Children originating from Asia except South-Asia had a higher prevalence of WHtR ≥ 0.5 (PR: 1.64, CI: 1.25-2.15) compared to non-immigrant background children. The adjustment for parental education did not substantially change the results. CONCLUSION: Children with immigrant background had higher prevalence of overweight/obesity than non-immigrant background children. The difference varied according to region of origin but not substantially according to parental education. There is a need for culturally acceptable preventative measures targeting the parents of immigrant background children.

Myelinosome-like vesicles in human seminal plasma: A cryo-electron microscopy study.

Seminal plasma is particularly rich in extracellular vesicles. Myelinosomes are membranous organelles described throughout the seminiferous epithelium of the testis but never reported in semen. Our aim was to determine the presence of myelinosomes in human seminal plasma. Transmission electron microscopy and cryo electron microscopy analysis of standard myelinosome preparation from TM4 Sertoli cells and human seminal plasma samples. We have specified by cryo-EM the morphological aspect of "standard" myelinosomes isolated from the culture media of TM4 Sertoli cells. Vesicles with the same morphological appearance were revealed in human seminal plasma samples. Human seminal plasma contains a population of large EV (average diameter 200 nm) whose morphological appearance resemble those of myelinosomes. Defining the specific biomarkers and functionalities of myelinosome in human seminal plasma are the concerns to be addressed in our further research.

Preeclampsia and gestational weight gain in the Norwegian Fit for Delivery trial.

OBJECTIVE: Excessive gestational weight gain is linked to risk of preeclampsia, but it is not clear whether the association is causal. The purpose of this paper was to examine gestational weight gain in the Norwegian Fit for Delivery study among women who developed preeclampsia compared to those who did not, and to further explore associations between weight gain and preeclampsia by including data on body composition (bioimpedance) assessed in the last trimester of pregnancy. RESULTS: A total of 550 women were eligible for the study. Women who developed preeclampsia gained more weight than women who did not (difference 3.7 kg, p = 0.004), with a 3.5 kg difference in total body water observed in week 36 (p = 0.040). Adjusted for age, education, pre-pregnancy body mass index (BMI), randomization, and fat mass, a one kg increase in GWG was associated with 1.3 times higher odds of preeclampsia (OR: 1.31, 95% CI 1.15-1.49, p < 0.001). An independent inverse association between fat mass in week 36 and odds of preeclampsia was observed (OR: 0.79, 95% CI 0.68-0.92, p = 0.002). Given the observed difference in total body water, these findings point to excess fluid as the component driving the association between gestational weight gain and preeclampsia in the present study. Trial registration The NFFD trial has the Clinical Trials registration: clinicaltrial.gov NCT0100168.

The effect of prenatal lifestyle intervention on weight retention 12 months postpartum: results of the Norwegian Fit for Delivery randomised controlled trial.

OBJECTIVE: To examine the effect of a prenatal lifestyle intervention on postpartum weight retention (PPWR). DESIGN: Randomised controlled trial. SETTING: Healthcare clinics in southern Norway. POPULATION: Healthy, nulliparous women with body mass index ≥19 kg/m2 , age ≥18 years, and singleton pregnancy of ≤20 gestational weeks. METHODS: Women were randomised to intervention (dietary counselling twice by phone and access to twice-weekly exercise groups during pregnancy) or control group (standard prenatal care). Intervention compliance was defined post-factum as attending dietary counselling and ≥14 exercise classes. MAIN OUTCOME MEASURES: PPWR (weight measured postpartum minus self-reported pre-pregnancy weight) and the proportion of women returning to pre-pregnancy weight. RESULTS: Of 606 women randomised, 591 were included in an intention-to-treat analysis of pregnancy outcomes and 391 (64.5%) were analysed 12 months postpartum. Mean PPWR was not significantly different between groups (0.66 kg for intervention versus 1.42 kg for control group, mean difference -0.77 kg, 95% CI -1.81, 0.28; P = 0.149). An increased proportion of intervention participants achieved pre-pregnancy weight (53% versus 43%, OR 1.50, 95% CI 1.003, 1.471; P = 0.045). However, the difference was not statistically significant when we adjusted for missing data (adjusted odds ratio (OR) 2.23, P = 0.067) using logistic mixed-effects models analysis. Women compliant with intervention had significantly lower PPWR than control participants, also after adjusting for potential confounders (adjusted mean diff -1.54 kg, 95% CI -3.02, -0.05; P = 0.039). CONCLUSIONS: The Norwegian Fit for Delivery intervention had little effect on PPWR, although women who were compliant with the intervention demonstrated significantly lower PPWR at 12 months. TWEETABLE ABSTRACT: Norwegian Fit for Delivery RCT: little effect of lifestyle intervention on weight retention 1 year postpartum.

Actual and perceived weight status and its association with slimming and energy-balance related behaviours in 10- to 12-year-old European children: the ENERGY-project.

BACKGROUND: Both parents' and children's perception of children's weight status may be important predictors of slimming and energy-balance related behaviours, independent of children's actual weight status. OBJECTIVES: We examined the cross-sectional association of children's self-reported slimming and energy-balance related behaviours with children's (i) actual, (ii) self-perceived and (iii) parent-perceived weight status. METHODS: Data of 10- to 12-year-old European children and their parents were used. Multilevel logistic and linear regression analyses were performed, adjusting for age, gender, parental weight controlling behaviours, education, marital status and ethnicity. RESULTS: Independent of their actual weight status, a higher proportion of children reported slimming when they or their parents perceived them as too fat. Children's self-perceived weight status was more strongly associated with slimming than their parents' perception or their actual weight status. Moreover, children who perceive themselves as overweight reported less physical activity and more screen time. Children whose parents perceive them as overweight reported less physical activity. CONCLUSIONS: Children's own perception of their weight status appears to be more important for their self-reported slimming than their actual or their parent's perceptions of their weight status. Additionally, children's self-perceived weight status seems important in engaging more physical activity and reduces screen time.

Lifestyle intervention to limit gestational weight gain: the Norwegian Fit for Delivery randomised controlled trial.

OBJECTIVE: To examine whether a lifestyle intervention in pregnancy limits gestational weight gain (GWG) and provides measurable health benefits for mother and newborn. DESIGN: Randomised controlled trial. SETTING: Healthcare clinics of southern Norway. POPULATION: Healthy, non-diabetic, nulliparous women, aged ≥18 years, with a body mass index of ≥19 kg/m2 , and with a singleton pregnancy at ≤20 weeks of gestation. METHODS: Women were randomised to an intervention group (with dietary counselling twice by telephone and access to twice-weekly exercise groups) or to a control group (with standard prenatal care). Participants were measured three times during pregnancy and at delivery, and newborns were measured at delivery. Hospital records were reviewed for outcomes of pregnancy and delivery. Assessors were blinded to group allocation. Analysis was performed by intention to treat, assessing GWG using the Student's t-test and linear mixed models, and comparing proportions using the chi-square test. MAIN OUTCOME MEASURES: GWG, rates of pregnancy complications and operative deliveries, and newborn birthweight. RESULTS: A total of 606 women were randomised. Of these, 591 were analysed, with 296 in the intervention group and 295 in the control group. At term, the mean GWG from pre-pregnancy was 14.4 kg for the intervention group and 15.8 kg for the control group (mean difference 1.3 kg; 95% confidence interval, 95% CI 0.3-2.3 kg; P = 0.009). There was no significant difference between groups in the frequency of pregnancy complications or operative deliveries. The intervention demonstrated no effect on the mean birthweight of term infants, or on the proportion of large newborns. CONCLUSIONS: The Norwegian Fit for Delivery lifestyle intervention in pregnancy had no measurable effect on obstetrical or neonatal outcomes, despite a modest but significant decrease in GWG. TWEETABLE ABSTRACT: Norwegian Fit for Delivery RCT: reduced gestational weight gain, unchanged birthweight and obstetric outcomes.

Is there such a thing as sustainable physical activity?

There is a global need to diminish climate gas emissions, and a simultaneous call for enhanced levels of physical activity. Increased physical activity entails reduced risk for overweight and chronic diseases, as well as a potential to reduce transport's major contribution to global CO2 emissions. However, increased physical activity level also implies increased energy expenditure. Therefore, we aim to introduce the concept of sustainable physical activity, and to suggest certain physical activity habits due to their potentially sustainable properties. Worldwide, a third of adults and four fifths of adolescents ought to be more physically active in order to comply with current physical activity recommendations. Yet, considering upcoming resource challenges, types of physical activity should be taken into account. Active transportation represents carbon-friendly means of transportation as well as an opportunity for enhanced physical activity. Physical activity conducted in the local community is likely to favor sustainability through less use of fossil fuel, as it makes transportation redundant. Moreover, going "back to basic", using less equipment and appliances for everyday tasks could contribute toward energy balance through increased physical activity, and could decrease resource use. Finally, balancing food intake and energy expenditure would require less food production with accompanying energy savings.

Effect of a diet intervention during pregnancy on dietary behavior in the randomized controlled Norwegian Fit for Delivery study.

A mother's diet during pregnancy has the potential to influence both her own and her child's short- and long-term health. This paper reports the effects of a randomized controlled diet intervention during pregnancy on dietary behavior post-intervention as reported in late pregnancy. The diet intervention was part of a lifestyle intervention targeting both diet and physical activity behaviors among nulliparous women participating in the randomized controlled Norwegian Fit for Delivery study (NFFD). Eligible women were enrolled in early pregnancy from eight healthcare clinics in southern Norway between 2009 and 2013. The diet intervention was based on 10 dietary recommendations that were conveyed during two counseling sessions by phone and in a pamphlet describing the recommendations and their simplified rationale. A diet score was constructed from a 43-item food frequency questionnaire (FFQ) and used to assess intervention effect on dietary behavior (score range 0-10). Between-group dietary differences post-intervention were estimated with analysis of covariance, with adjustment for baseline diet. A total of 508 women completed the FFQ both at baseline and post-intervention. There were no between-group differences in diet score and subscales at baseline. Post-intervention, the intervention group had higher overall diet score (control: 4.61, intervention: 5.04, P=0.013) and favorable dietary behavior in seven of the 10 dietary domains: 'consumption of water relative to total beverage consumption' (P=0.002), 'having vegetables with dinner' (P=0.027), 'choosing fruits and vegetables for between-meal snacks' (P=0.023), 'buying small portion sizes of unhealthy foods' (P=0.010), 'limiting sugar intake' (P=0.005), 'avoiding eating beyond satiety' (P=0.009) and 'reading food labels' (P=0.011). The NFFD diet intervention improved dietary behavior. Potential long-term clinical influence in mother and child will be investigated in further studies.

Television in the bedroom and increased body weight: potential explanations for their relationship among European schoolchildren.

AIMS: A television in the bedroom is associated with measures of adiposity. We aimed to test if this association is mediated by any of (i) time spent watching television, (ii) sleep duration, (iii) physical activity level or (iv) consumption of soft drinks. METHOD: Data were from 7234 boys and girls aged 10-12 years in European countries involved in the EuropeaN Energy balance Research to prevent excessive weight Gain among Youth project (Belgium, Greece, Hungary, the Netherlands, Norway, Slovenia and Spain). Waist circumference, height and weight were measured. The presence of a bedroom television, television viewing time, sleep duration, physical activity time and soft drink consumption were assessed by standardized questionnaires. RESULTS: Almost 40% of schoolchildren had a bedroom television, with the highest percentage among Hungarian children (65%) and lowest for Belgian, Slovenian and Spanish children (all ≈28%). A television in the bedroom was positively associated with time spent watching television, soft drink consumption and overweight and obesity (all P < 0.001). The relationship between a television in the bedroom and measures of body size was partly mediated by total television viewing time (proportion mediated for waist circumference 8.9%; for body mass index 8.3%) but not sleep duration, physical activity time or soft drink consumption. CONCLUSION: The strong association between a television in the bedroom and adiposity was at least partially mediated by television viewing time. The large proportion of European schoolchildren with a television in their bedroom is of concern. Parents should be aware of the potential consequences when placing a television in a child's bedroom and children should limit viewing time.

Differences in weight status and energy-balance related behaviours according to ethnic background among adolescents in seven countries in Europe: the ENERGY-project.

OBJECTIVE: The aim of this study was to explore differences in weight status and energy balance behaviours according to ethnic background among adolescents across Europe. METHODS: A school-based survey among 10-12-year-old adolescents was conducted in seven European countries. Weight, height and waist circumference were measured; engagement in physical activity, sedentary and dietary behaviour, and sleep duration was assessed by child and parent-report. A distinction between native and non-native ethnic background was based on language spoken at home, and the parents' country of birth. Analyses were conducted with and without adjustment for parental education. RESULTS: With valid data on both indicators of ethnic background for 5149 adolescents, 7307 adolescents (52% girls; 11.6 ± 0.7 years) participated. Significantly higher prevalence of overweight, obesity, body mass index and waist circumference were observed among non-native compared with native adolescents. Non-native adolescents had less favourable behavioural patterns (sugary drinks, breakfast skipping, sport, TV and computer time, hours of sleep) with the exception of active transport to school. Similar patterns were observed for both indicators of ethnicity, and in most of the separate countries; however, in Greece, weight status indicators were better among non-native adolescents. After adjustment for parental education, most differences remained significant according to country of origin of the parents, but not according to language spoken at home. CONCLUSION: Adolescents of native ethnicity of the country of residence have, in general, more favourable weight status indicators and energy balance-related behaviours than adolescents of non-native ethnicity across Europe.

The association between cycling to school and being overweight in Rotterdam (The Netherlands) and Kristiansand (Norway).

Active transportation is a behavior that might contribute to energy balance. However, no clear association between active commuting to school and weight status has been reported in the international literature. Also, new studies indicate that cycling to school might have a greater health potential than walking to school. The purpose of the present study is to assess the potential association between cycling to school and weight status in two European cities, Rotterdam and Kristiansand, where cycling to school remains common. Data from two studies, ENDORSE (Rotterdam) and Youth in Balance (Kristiansand), were used including, respectively, 1361 and 1197 adolescents with mean ages of 14.1 and 14.4 years. The adolescents were categorized as cyclist or non-cyclist based on questionnaires on the usual mode of transportation to school. A total of 25% and 18% were categorized as overweight, and 35% and 31% were categorized as cyclists, in Rotterdam and Kristiansand, respectively. In multilevel logistic analyses, after adjusting for potential moderators, the odds ratios for cyclists being overweight compared with non-cyclists were, respectively, 0.63 (95% CI=0.45-0.89) and 0.52 (95% CI=0.34-0.78) in Rotterdam and Kristiansand. The results presented clearly show a negative association between cycling to school and overweight among adolescents both in Rotterdam and in Kristiansand.

Appreciation and implementation of a school-based intervention are associated with changes in fruit and vegetable intake in 10- to 13-year old schoolchildren--the Pro Children study.

The purpose was to investigate the degree of implementation and appreciation of a comprehensive school-randomized fruit and vegetable intervention program and to what extent these factors were associated with changes in reported fruit and vegetable intake. The study was conducted among 10- to 13-year old children exposed to the intervention during the school year 2003-04 in Norway, Spain and the Netherlands. Children, parents and teachers completed questionnaires regarding (i) the implementation of the school curriculum, (ii) parental involvement, (iii) distribution of fruit and vegetables at school, (iv) children's appreciation of the project and (v) children's intake levels. Univariate analyses of covariance and multilevel multivariate regression analyses indicated that teacher-reported level of implementation of the school curriculum and schoolchildren's appreciation of the project were important determinants of changes in intake. The results point to the importance of optimal implementation of an attractive school curriculum.

Modulation of lymphocyte function with inhibitory CD2: loss of NK and NKT cells.

Analysis of the NK cell developmental pathway suggests that CD2 expression may be important in regulating NK maturation. To test this hypothesis, we developed mice containing only an inhibitory CD2 molecule by linking the extracellular domain of CD2 to an intracellular immunoreceptor tyrosine-based inhibitory motif (ITIM) motif. Mice containing the CD2 Tg(ITIM) transgene, introduced into a CD2 KO background, have no morphologically detectable lymph nodes, although development of the thymus appears normal. In addition, these mice had major loss of both NK and NKT subsets in peripheral organs, while T and B cell frequencies were intact. Expression of CD2 was low on T cells and lacking on B cells and functional defects were observed in these populations. NKT cells expressing CD4 were absent, while the CD8+ and double negative NKT cells were retained. Small subsets of NK cells were detected but expression of CD2 on these cells was very low or absent, and their maturation was impaired. Based on the phenotype described here, we believe that these mice represent a unique model to study lymphoid organ and lymphocyte development.

Wild berries: a good source of omega-3.

It has been reported that some wild green vegetables are good sources of alpha-linolenic acid (ALA, an essential omega-3 fatty acid). Using available data from the Norwegian food composition table, the present study shows that three common Nordic berries (blueberry, cloudberry and cowberry) on average contain 0.7 g of fat (=21% of total energy) and 0.25 g ALA (=36% of total fat) per 100 g, which is quite similar to what has been reported for the ALA-rich wild green vegetables. In addition, this study shows that a hypothetical replacement of 5% of Norwegian 8th grade girls' diet, with a similar energy amount of wild berries, would significantly improve the diet - also improve intake of nutrients not commonly associated with berries.

Free school fruit--sustained effect 1 year later.

This study reports the effect of a school-randomized fruit and vegetable intervention consisting of a subscription to the Norwegian School Fruit Programme at no parental cost, and the Fruit and Vegetables Make the Marks (FVMM) educational programme, both delivered in the school year of 2001-02. Nine randomly chosen schools received the intervention and 10 schools served as control schools. Participating pupils completed questionnaires at baseline (September 2001), at Follow-up 1 (May-June 2002) and at Follow-up 2 (May 2003). A total of 517 pupils (84%; mean age, 11.3 years at baseline) participated in all three surveys. At both Follow-up 1 and Follow-up 2, strong intervention effects were observed for all-day fruit and vegetable intake (effect sizes were 0.6 and 0.5 portions, respectively). The sustained effect at Follow-up 2, 1 year after the end of the intervention, can partly be explained by greater participation rates in the School Fruit Programme (standard paid subscription). We conclude that the effects observed are most likely due to the no-cost subscription and not due to the FVMM educational programme, and that providing pupils with a piece of fruit or a vegetable at school at no cost for the parents is an effective strategy to increase school children's intake of fruit and vegetables. The effect is also sustained 1 year after the end of the no-cost subscription, providing increased health benefits.

Outcome and process evaluation of a Norwegian school-randomized fruit and vegetable intervention: Fruits and Vegetables Make the Marks (FVMM).

This study reports the effect of the Fruits and Vegetables Make the Marks intervention, a school-based fruit and vegetable intervention consisting of a home economics classroom component and parental involvement and encouraged participation in the Norwegian School Fruit Programme, all delivered during the school year of 2001-02. Nine randomly chosen schools received the intervention and 10 schools served as control schools. Participating pupils completed questionnaires at baseline (September 2001), at Follow-up 1 (May-June 2002) and at Follow-up 2 (May 2003). A total of 369 pupils (69%; mean age, 11.3 years at baseline) participated in all three surveys. No effect of the intervention was found for intake of fruit and vegetables eaten at school or all day, neither at Follow-up 1 nor at Follow-up 2. On analysing the effects on potential mediators, significant differences between intervention and control groups were found for Awareness of the five-a-day recommendations only. The intervention programme was rated as very good by the teachers, and the pupils reported that they enjoyed it. However, the intervention failed to change fruit and vegetable intake, probably because it did not succeed in changing the pupils' preferences for or the accessibility of fruit and vegetables--the two strongest correlates of children's fruit and vegetable intake.

Validity and reproducibility of self-reported intake of fruit and vegetable among 6th graders.

OBJECTIVE: Reproducible and valid methods for measuring fruit and vegetable consumption among young school children are urgently needed. The aim of this study was to test the reproducibility and the validity of a newly developed questionnaire on the intake of fruit and vegetable among Norwegian 6th graders. The questionnaire consisted of a 24-h recall part and a food frequency part. DESIGN: A total of 114 pupils completed the questionnaire two times 14 days apart, and another 85 pupils completed the questionnaire and 7-day food diaries. SUBJECTS: Pupils of 6th grade with a mean age of 11.9 y. RESULTS: Spearman correlation coefficients between the frequency part of the questionnaire administered two times varied from 0.62 for fruit to 0.83 for potato, and no difference was seen between the average intakes from the two 24-h recalls. The 24-h recall part of the questionnaire gave higher estimates for the average intake of fruit and juice compared to the 7-day record, while no difference was observed for vegetable intake. Spearman correlation coefficients between the frequency part and the records varied from 0.21 for fruit and potato to 0.32 for the total intake of fruit and vegetable. CONCLUSION: Both the 24-h recall and the frequency part gave a consistent response on separate occasions over the test-retest study period. The 6th graders were capable of recording yesterday's intake of vegetable, but overestimated the intake of fruit and juice. The ability to rank subjects based on the frequency part was rather low.

Human B cell activation by autologous NK cells is regulated by CD40-CD40 ligand interaction: role of memory B cells and CD5+ B cells.

NK cells are a subpopulation of lymphocytes characterized primarily by their cytolytic activity. They are recognized as an important component of the immune response against virus infection and tumors. In addition to their cytolytic activity, NK cells also participate either directly or indirectly in the regulation of the ongoing Ab response. More recently, it has been suggested that NK cells have an important role in the outcome of autoimmune diseases. Here, we demonstrate that human NK cells can induce autologous resting B cells to synthesize Ig, including switching to IgG and IgA, reminiscent of a secondary Ab response. B cell activation by the NK cell is contact-dependent and rapid, suggesting an autocrine B cell-regulated process. This NK cell function is T cell-independent, requires an active cytoplasmic membrane, and is blocked by anti-CD40 ligand (anti-CD154) or CD40-mIg fusion protein, indicating a critical role for CD40-CD40 ligand interaction. Depletion studies also demonstrate that CD5+ B cells (autoreactive B-1 cells) and a heterogeneous population of CD27+ memory B cells play a critical role in the Ig response induced by NK cells. The existence of this novel mechanism of B cell activation has important implications in innate immunity, B cell-mediated autoimmunity, and B cell neoplasia.

Activating Ly-49 NK receptors: central role in cytokine and chemokine production.

In an attempt to understand potential novel functions of receptors in vivo, we evaluated gene expression after cross-linking the activating Ly-49D mouse NK receptor. Gene expression was evaluated using a mouse GEM 2 microarray chip (Incyte Genomics, St. Louis, MO). Each chip displays a total of 8734 elements. The strongly induced genes fell into two categories: 1) soluble factors and 2) apoptotic genes. The majority of the strongly induced mRNAs as analyzed by microarray hybridization were chemokine genes. RNase protection assays and chemokine protein production analysis validated the microarray results, as cross-linking the Ly-49D mouse NK receptor induced high levels of IFN-gamma, lymphotactin, macrophage-inflammatory protein (MIP)1alpha, and MIP1beta. This gene expression was specific because other chemokines were not induced by anti-Ly-49D receptors. In addition, a series of pharmacological inhibitors were used to identify the key signaling pathways involved in the cellular response. The primary Ly-49D signaling for IFN-gamma production is predominantly mediated through Src kinase pathways involving membrane proximal events, whereas MIP1alpha and MIP1beta gene induction is more complex and may involve multiple biochemical pathways. Thus, we conclude that a primary role for the activating NK receptors in vivo may be to trigger soluble factor production and regulation of the immune response. This would place NK cells and their activating Ly-49 receptors as important initiators of microbial immunity and key elements of the innate immune system.