Background Both human leukocyte antigen (HLA)-DRB1*15 and Epstein-Barr virus infection presenting as infectious mononucleosis (IM) are recognized as risk factors for multiple sclerosis (MS). However, their combined effect and possible interaction on MS risk is not known. Objective To assess the association between HLA-DRB1*15 and risk of MS in persons with and without IM. Methods We compared the prevalence of DRB1*15 in MS patients with ( n = 76) and without ( n = 1,836) IM with the corresponding distributions in blood donors with ( n = 62) and without ( n = 484) IM histories. This allowed us to estimate the relative risk of MS associated with DRB1*15 in the presence and absence, respectively, of previous IM. We then estimated the interaction between DRB1*15 and IM as the ratio of the two individual odds ratios. Results In IM-naïve individuals, DRB1*15 carried a 2.4-fold (95% confidence interval [CI], 2.0–3.0) increased MS risk. In contrast, among persons with IM history, DRB1*15 was associated with a 7.0-fold (95% CI, 3.3–15.4) increased MS risk. Thus, the MS risk conferred by HLA-DRB1*15 was 2.9 (95% CI, 1.3–6.5)-fold stronger in the presence than in the absence of IM. Combined with previous results, this result indicates that DRB1*15-positive persons with a history of IM may be at a 10.0-fold (95% CI, 6.0–17.9) increased risk of MS compared with persons who are DRB1*15 and IM-naïve. Conclusion DRB1*15 and IM may act in synergy causing MS.

Background and Objectives: Even with appropriate donor deferrals and advanced screening tests, the risk of disease transmission through blood transfusion cannot be completely disregarded. Efficient monitoring of possible disease transmission between blood donors and recipients should be an important component of a comprehensive haemovigilance system.Materials and Methods: We assembled the Scandinavian Donations and Transfusions (SCANDAT) database, with data on virtually all blood donors and recipients who have been registered at least once in any of the computerized local blood bank databases in Sweden and Denmark since the start of computerized registration in 1966. The records of these individuals, with their entire computerized donation and/or transfusion histories and all donor-component-recipient connections, were linked to nationwide population and health registers to attain essentially complete follow-up for up to 36 years regarding reproduction, hospital morbidity, cancer, and death.Results: After data cleaning, the database contained 1 134 290 blood donors who contributed 15 091 280 records of donations and 1 311 079 recipients who received 11 693 844 transfusions. The data quality in the existing data sources was satisfactory. From the data obtained from local blood banks, 4.6%, 1.6%, and 6.4% of the person, donation, and transfusion records, respectively, had to be discarded after review of the legitimacy of recorded values, and comparisons with independent, external databases.Conclusion: It is possible to use existing computerized data, collected in routine health care, in haemovigilance systems for monitoring long-term outcome and disease concordance in blood donors and transfusion recipients.

BACKGROUND: The neutrophil‐specific antigens NA1, NA2, and SH are well‐recognized allotypic forms of FcγRIIIB. Individuals carrying all three FcγRIIIB genes were recently described.STUDY DESIGN AND METHODS: A Danish population (n = 200) was typed for NA1, NA2, and SH by polymerase chain reaction with sequence‐specific primers (PCR‐SSP). Twelve individuals with three FcγRIIIB genes were further genotyped by PCR‐based restriction fragment length polymorphism and by DNA sequencing. Family studies were performed on three individuals who carry three FcγRIIIB genes.RESULTS: The gene frequencies for NA1, NA2, and SH were 0.365, 0.635, and 0.030, respectively. In eight individuals (4%), all three FcγRIIIB genes were identified. All 12 SH+ individuals were NA1+.CONCLUSION: The NA1, NA2, and SH gene frequencies observed in Danes are similar to those in other white populations. The distribution of FcγRIIIB genotypes in the Danish population strongly indicates that the NA and the SH systems are located in two closely linked loci and that SH is closely linked to NA1. Finally, a new PCR‐SSP was developed to distinguish NA2 from SH.

Hereditary haemochromatosis (HH), a condition of abnormal iron metabolism which leads to iron overload and organ damage, previously known as bronze diabetes or idiopathic haemochromatosis, is the most common disease-producing genetic disorder among Europeans. Two mutations, C282Y and H63D, are described for the candidate gene, HFE, reported as being responsible for the disease. Since molecular testing of these mutations will be of value in early diagnosis of haemochromatosis, the aim of this study was to develop a simple, fast and inexpensive technique for the determination of the polymorphism in the HFE gene on a large scale. We designed sequence-specific primers for polymerase chain reaction (PCR-SSP) and tested 200 randomly selected healthy Danes and found the result completely comparable to results obtained by a previously described method, PCR-RFLP. The gene frequencies in the Danish population are similar to reported results for the White population, with a frequency of 0.068 for the C282Y mutation and a frequency of 0.128 for the H63D mutation.

The aim of this study was to compare the frequencies of five HLA-E alleles in 82 women with recurrent spontaneous abortions with that of 150 random Danish controls. PCR sequence-specific oligonucleotide typing was carried out to detect polymorphism in exons 2 and 3 of the HLA-E gene. In informative samples sequencing of these two exons was also undertaken to confirm the presence of the HLA-E*01031 allele. HLA-E*0101, HLA-E*01032 and HLA-E*01031 were detected with frequencies of 56.7%, 33.6% and 9.6% in controls and 58,5%, 32.9% and 8.5% in patients with recurrent abortion, respectively. No HLA-E*0102 and E*0104 alleles could be detected. Since the HLA-E allele distribution was similar in women with recurrent spontaneous abortion and controls, it is suggested that maternal HLA-E polymorphism per se does not play any role in the pathogenesis of this disorder of pregnancy.

Background and objectives: The possible immunosuppressive action of blood transfusion has aroused great interest recently, particularly with respect to its effects on tumor growth and recurrence rate of malignant disease. Materials and methods: The effect of blood transfusion on lymphocyte subpopulations and NK cell function preoperatively and 6 months postoperatively was studied in 129 patients treated with elective surgery for colorectal malignancy. Forty-two patients (33%) received blood transfusions, 21 of them randomly allocated to receive leukocyte-depleted blood products. Investigation was by means of conventional laboratory methods. Results: In 21 patients receiving a median of 3 units of non-leukocyte-depleted blood products (NLD), a significant reduction in CD4+ lymphocytes (44% vs. 40%, p < 0.01) occurred. In contrast, no significant changes in CD4+ lymphocytes were observed in the 21 patients transfused with leukocyte-depleted blood products (LD). However, with respect to lymphocyte subpopulations and NK cell function, differences between the NLD and LD groups were not significant. There was a marginal decrease in HLA-DR+ lymphocytes in the NLD patients without a history of previous transfusion. Conclusions: There seems to be no major change in lymphocyte subpopulations and NK cell function 6 months after blood transfusion. Thus we cannot confirm our previous findings of a reduced number of CD20+ cells after blood transfusion.

There is now evidence that the classical HLA class I molecule HLA-C is expressed on extravillous trophoblasts together with non-classical HLA-G molecules. Since clones of NK-cells are inhibited differently by supertypic epitopes associated with HLA-C and -B alleles we found it of interest to study HLA-C and -Bw polymorphism in 35 couples with recurrent miscarriage and 30 control couples with normal fecundity. All HLA assignments were undertaken by DNA techniques. The distribution of HLA-C alleles or the HLA-C associated supertypic epitopes recognized by NK1 or NK2 clones was not significantly different between patients and controls. The distribution of couples according to the number of NK1 and NK2 epitopes in the couple was similar in patients and controls. With respect to the HLA-Bw epitopes recognized by NKB1 clones, in 46% of the couples with recurrent miscarriage none of the spouses carried the HLA-Bw4 epitope compared with only 17% of the control couples (P < 0.02). It is concluded that the HLA-Bw4 epitope is carried more frequently by couples with normal fecundity than couples with recurrent miscarriage. The fetuses of couples with recurrent miscarriage are thus expected to lack expression of HLA-Bw4 epitopes on the trophoblast more often than fetuses of normal couples which might be of importance for the inhibition of NK-cell mediated antitrophoblast cytotoxicity.

Polymerase chain reaction in combination with sequence-specific oligonucleotide probes were used to analyze nine HLA-B27 subtypes among 51 healthy HLA-B27 positive Danish blood donors and 30 Danish HLA-B27 positive patients with ankylosing spondylitis (AS). In the group of healthy Danes we found two subtypes, B*2705 (90.2%) and B*2702 (9.8%), however, among the AS patients only the B*2705 subtype was detected. We did not find a significant evidence for associations between AS and a particular HLA-B27 subtype in a Danish population.

This study reports the first data on gene frequencies of platelet alloantigens HPA-1, HPA-2, HPA-3, HPA-4 and HPA-5 in a population of unrelated Danish blood donors using PCR-techniques. The observed gene frequencies fit the Hardy-Weinberg equilibrium, and the calculated phenotype frequencies are similar to those obtained in other Caucasian populations: HPA-1a and -1b occur in 96.6% and 30.3% of 557 unrelated respectively. HPA-2a and -2b in 99.4% and 15.9% of 163 tested, HPA-3a and -3b in 88.3% and 63.2% of 163 tested, HPA-4a and -4b in 100% and 0% of 131 tested, and finally HPA-5a and -5b in 100% and 15.7% of 427 tested. It is a major technical improvement to use PCR techniques for genomic typing of HPA. Not only is it possible to perform HPA typings in severely thrombocytopenic patient and on amniotic fluid cells of the fetus of alloimmunized mothers, but it must be expected that accuracy of the HPA typing will increase considerably, as has been the case with genomic HLA class II typing. Finally, use of PCR technique combined with allele-specific primers is suitable for accurate large scale typing of platelet donors, which may be useful in special clinical settings.

The effect of dietary supplementation with n-3 polyunsaturated fatty acids (PUFAs) on the production of free oxygen radicals from activated neutrophils was investigated in healthy subjects, using chemiluminescence. In the first study 22 persons were give 4 g n-3 PUFAs daily for 6 weeks. There was a median reduction of chemiluminescence from neutrophils stimulated with opsonized zymosan of 37% (p < 0.001). The median content of eicosapentaenoic acid in platelets, used as an indicator for cellular fatty acid profile, increased from 0.70 to 2.80% (p < 0.001), and there was a significant negative correlation between the chemiluminescence signal and the content of eicosapentaenoic acid in platelets (p < 0.001). In a second, low-dose study 24 persons were allocated to daily supplementation with either 0.65 g n-3 PUFAs or with a control oil for 6 weeks. Compared to the control group there was a median reduction of 38 and 44% in chemiluminescence from neutrophils stimulated with opsonized zymosan and phorbol,12-myristate,13-acetate (PMA), respectively. Neither of these differences, however, was statistically significant. These findings lend support for a possible role of n-3 PUFAs in the management of inflammatory disorders.

HLA-DR and -DQ typings were performed by a combination of RFLP and PCR-SSP techniques in 234 Danish women with at least three consecutive unexplained fetal losses (recurrent fetal losses) and 360 controls and the DRB1, DQA1 and DQB1 alleles were deduced. In the total group of patients, the frequency of no DRB1-DQA1-DQB1 haplotype was significantly increased compared with controls. In the subgroup of 97 women with four or more fetal losses (multiple fetal loss group), the frequency of women carrying the DRB1*0101, DQA1*0101, DQB1*0501; DRB1*0102, DQA1*0101, DQB1*0501 and DRB1*0103, DQA1*0101, DQB1*0501 haplotypes or the DRB1*0301, DQA1*0501, DQB1*0201 haplotype were significantly increased compared with controls (RR=2.1; p(c)<0.05 with regard to former three haplotypes combined and RR=2.2; p(c)<0.05 for the latter). The frequency of women with at least one of the four haplotypes was significantly (p<0.002) increased with the number of previous fetal losses in the women's history. Analysis of the DQA1 and DQB1 phenotypes in women with at least four fetal losses showed that DQA1*0501 and DQB1*0501 were increased compared with controls (RR=1.9; p(c)<0.05 and RR=2.2; p(c)<0.025, respectively). Analysis of DRB1-DQA1-DQB1/DRB1-DQA1-DQB1 genotypes suggested that genotypes comprising both DQA1*0501 and DQB1*0501 alleles (in trans) exhibited a higher RR for experiencing at least four fetal losses (RR=3.4, p=0.002) than each of the alleles did alone. Genotypes comprising a DQB1 allele encoding a beta chain negative for aspartate in position 57 were associated with an increased RR (2.3; p<0.01) for multiple fetal losses and the etiologic fraction was high (0.49). The results suggest that genes or gene-sequences, linked to the DRB1*0101, DQA1*0101, DQB1*0501; DRB1*0102, DQA1*0101, DQB1*0501; DRB1*0103, DQA1*0101, DQB1*0501 and DRB1*0301, DQA1*0501, DQB1*0201 haplotypes, confer susceptibility to multiple fetal losses. These alleles/gene-sequences are presumably located in the DQA1 and DQB1 loci and may elicit their effect by mediating an autoimmune reaction against one or more trophoblast antigens.

To elucidate the possible influence of previous blood transfusion on immune functions, the transfusion history of 153 patients admitted to hospital for elective colorectal surgery was correlated with lymphocyte subsets and natural killer (NK) cell function. The subsets determined were CD2, CD3, CD4, CD8, CD16, CD20, CD56, CD57 and HLA-DR-positive. The NK cell function was determined by measuring the killing capacity against cFDA-labelled K562 target cells monitored via a flow-cytometer. We found that 42 patients (27%) had been transfused before surgery, of these 13 had been transfused less than 30 days before surgery and 29 (19%) transfused more than 30 days before (median 10 years, range 0.1-37 years). In transfused patients, we found a significantly reduced number of B lymphocytes (CD20; p = 0.01), a reduction in HLA-DR-positive cells (p = 0.02) and a just significant reduction of NK cell function in transfused compared to nontransfused patients. The reduction in NK cell function is marginal and the NK cell function is within normal range, and probably without clinical significance. Reduction in NK cell function has been described before, whereas the reduction in B cells has not been reported earlier. The results may suggest an impaired humoral immunity and a minor reduction in cellular immunity in patients following blood transfusion.

In a previous case-control study of women with unexplained recurrent miscarriages we reported that the frequency of women positive for each of the two histocompatibility (HLA) types HLA-DR1, Br and HLA-DR3 was increased in a subset of patients with a history of four or more miscarriages. In the present study we examined whether the increased frequency of the two HLA types in this subset of patients indicated that they would result in a poor pregnancy prognosis. We related pregnancy outcomes to the mothers' HLA-DR type in a prospective study of a well-defined, closely supervised group of 94 women with unexplained recurrent miscarriages who had achieved intra-uterine pregnancy in the course of one of two prospective placebo-controlled trials concerning the efficacy of immunotherapy. Of the patients who were HLA-DR1, Br and/or HLA-DR3 positive 62% miscarried their next pregnancy compared with 29% of the patients negative for the two HLA types [relative risk of miscarriage in the former group = 2.2 (P < 0.002) unadjusted, and 1.8 (P = 0.025) when adjusted for the number of previous miscarriages]. The results suggest that Danish women with unexplained recurrent miscarriages who are positive for HLA-DR1, Br and/or -DR3 display a poorer pregnancy outcome than patients negative for these types.

Occurrence of clinical neurologic multiple sclerosis (CNMS) among resident Faroese began between 1943 and 1973 and comprised three epidemics. The occupation by British forces for 5 years during World War II was interpreted to have been of major importance for the occurrence of these epidemics and led us to believe that CNMS is the rare, late result of a single, widespread, systemic and specific infectious disease which we have labelled the primary MS affection (PMSA). In this study we describe the occurrence of genetic markers of the HLA system in 16 Faroese MS patients, 25 of their siblings, 30 unrelated healthy neighbors and spouses to MS patients, 18 healthy controls from areas where no MS cases have been detected, and 80 unrelated normal Faroese. These studies show no significant deviations of HLA class I antigens, whereas the class II antigens do deviate: 50% of the Faroese MS patients carry the HLA-DR2 (DQ1/DRB 15) antigen, compared to a frequency of 15-20% among the control groups. Also the group of siblings of MS patients showed an increased frequency of DR4 (72%) compared to normal frequency among MS patients and other normal controls (43-47%). However, if DR15-positive individuals were excluded, this difference was further reduced. If PMSA was widespread within this group, DR4 or some closely associated genetic marker may confer protection against PMSA developing into CNMS. The occurrence of CNMS in these epidemics seems therefore associated to HLA class II-linked genetic factors similar to those found in studies of other caucasians with MS. This observation seems important in understanding the pathogenesis of this disease.