Regulatory T-Cells in the Graft and the Risk of Acute Graft-Versus-Host Disease After Allogeneic Stem Cell Transplantation

BACKGROUND

FOXP3+ regulatory T-cells (Treg) are important regulators of allo-reactivity and may therefore represent an important predictor for the risk of graft versus-host disease (GVHD) after allogeneic stem cell transplantation.

METHODS

To determine the clinical significance of Treg-content in stem cell grafts, we analyzed 58 human leukocyte antigen (HLA)-identical sibling donors (34 patients received myeloablative and 24 patients reduced intense conditioning regimens) and correlated the Treg frequency with clinical outcome after stem cell transplantation (SCT).

RESULTS

A mean value of 9.1 x 10(6) CD4+ FOXP3+ Treg per kg body weight (bw) of the recipient was transplanted (ranging from 0.7 to 33.7 x 10(6) Treg/kg bw). Graft content of Treg correlated with mononuclear cells and CD3+ T-cells. Patients receiving low numbers of Treg (Treg(low)) after myeloablative conditioning for SCT had a significantly increased cumulative incidence of 76% for acute GVHD when compared with 23% for individuals receiving high numbers of Treg (Treg(high)). This observation, however, was not made in patients after reduced intense conditioning-SCT. Notably, relapse rate was not significantly different between Treg(low) and Treg(high) patients in either patient group and overall survival was even increased in Treg(high) patients after myeloablative SCT. Finally, low Treg graft levels represent an independent prognostic factor in multivariate analysis for the appearance of acute GHVD.

CONCLUSION

Donor-derived Treg might be of particular significance for the development of acute GVHD after myeloablative SCT using HLA-identical sibling donors.

Lactate dehydrogenase isoenzymes of human semen

1. A lactate dehydrogenase isoenzyme present in human spermatozoa and semen was isolated and characterized biochemically in term of its pH for optimum activity and by means of K(m) values for lactate, NAD(+) and NAD analogues. The results were compared with those obtained with the human heart-type and the liver-type lactate dehydrogenase isoenzymes. 2. The enzyme was characterized by its resistance to digestion with different proteolytic enzymes. The time for 50% digestion in terms of residual dehydrogenase activity was compared with times obtained for the H(4)- and M(4)-types.

Donor cytomegalovirus seropositivity and the risk of leukemic relapse after reduced-intensity transplants

OBJECTIVES

Despite effective preemptive and prophylactic therapeutic strategies, cytomegalovirus (CMV) seropositivity of either recipient and/or donor still remains an important parameter for outcome even after reduced-intensity allogeneic stem cell transplantation (SCT). Whether CMV seropositivity of the donor might have an impact on leukemic relapse is unknown.

PATIENTS

Between June 1999 and February 2004 48 patients ineligible for conventional allotransplantation underwent reduced-intensity transplants at our institution. Twenty-seven (56%) patients had a CMV-seropositive donor.

RESULTS

While donor CMV seropositivity had no effect on overall survival, having a CMV-seropositive donor was associated with a significantly lower risk for relapse (20% vs. 52%, P = 0.02). The beneficial effect of a CMV-seropositive donor, however, was offset by a higher transplant-related mortality (42% vs. 19% in patients with a CMV-seronegative donor, P = 0.2). Donor CMV serostatus had no effect on the incidence of CMV infection/disease, and acute or chronic graft-vs.-host disease. Overall, 27 patients died during the observation period. Causes of death in patients with a CMV-seropositive donor were primarily transplant-related (11 vs. 4 in patients with CMV-seronegative donors), whereas leukemic relapse was the leading cause of death in patients with a CMV-seronegative donor (8 vs. 4 in patients with a CMV-seropositive donor, P = 0.038, chi-squared test). Multivariate Cox regression analysis showed risk category by the underlying disease and donor CMV seropositivity to be significant predictors of leukemic relapse following reduced-intensity transplants.

CONCLUSIONS

These preliminary results suggest a possible role of donor CMV serostatus on the risk of relapse following reduced-intensity allogeneic SCT.

Suppression of natural killer cells in the presence of CD34+ blood progenitor cells and peripheral blood lymphocytes

Abstract Mobilization of CD34 + peripheral blood progenitor cells (PBPCs) with granulocyte-colony stimulating factor (G-CSF) may induce functional alterations in peripheral blood lymphocyte (PBL) subsets. We and others have shown that natural killer (NK) cells from PBPC collections are less expandable in vitro than those obtained during steady-state hematopoiesis. We show here that the extent of this proliferation deficit is related to the number of circulating CD34 + cells in vivo at the time of PBPC apheresis. Likewise, addition of autologous CD34 + cells to unseparated PBL reduced the expansion of the NK-cell subset by 22.2% +/- 6.0% (n = 10; P <.005). In contrast, when using purified NK cells, their proliferation remained unimpaired by autologous CD34 + cells. Supernatants from CD34 + cells cultured with autologous PBLs had an inhibitory effect on proliferation of purified NK cells (n = 16; P =.03), indicating that an interaction between CD34 + cells and lymphocytes is essential for the suppressive effect on NK cells. To investigate the role of T cells in this interaction, intracellular cytokines were determined in T cells cultured for 7 days with or without autologous CD34 + cells. When cultured with CD34 + cells, the frequency of IL-2-producing CD4 + and CD8 + T cells was reduced by 19% and 24%, respectively, compared with T cells cultured alone (n = 7; P =.016). Interferon-gamma-producing T cells were slightly reduced ( P = not statistically significant [ns]). Finally, the influence of T cells and NK cells on the recovery of myeloid colony-forming cells (CFU-GMs) from purified CD34 + cells was examined. In the presence of T cells, 16% +/- 6% of the input CFU-GM recovered after 7 days, compared with 5% +/- 4% in the presence of NK cells (n = 5; P = ns). Our findings point to an inhibition of NK-cell proliferation mediated by an interaction of CD34 + cells and T cells occurring during PBPC mobilization with G-CSF.

Natural killer cell functions mediated by the neuropeptide substance P

The neuropeptide substance P (SP) can modulate a number of immunological functions in vitro and in vivo. Here, we investigated if SP boosts migration and cytotoxicity of natural killer cells, thus providing a further link between "innate immunity" and neurogenic inflammatory processes like asthma bronchiale. We demonstrate a dose-dependent effect of SP on natural killer cell migration with a maximal response at 10(-8) M SP. SP was shown to stimulate unstimulated as well as interleukin-2 (IL-2)-activated natural killer cells. Stimulation of natural killer cell migration was neurokinin-1 receptor dependent. Furthermore, mRNA encoding the neurokinin-1 receptor was demonstrated as being present in natural killer cells using RT-PCR while mRNA of the neurokinin-2 receptor was not detectable. Additionally, SP seems to influence specific cytotoxicity against Raji and K567 effector cells by a receptor-independent mechanism. In conclusion, our data indicate that functionally active neurokinin-1 receptors can be expressed by human natural killer cells. Substance P might therefore be a novel link between neural structures and innate immunity.

Sustained effects of pioglitazone vs. glibenclamide on insulin sensitivity, glycaemic control, and lipid profiles in patients with Type 2 diabetes

AIMS

This study compared the effects of 52 weeks' treatment with pioglitazone, a thiazolidinedione that reduces insulin resistance, and glibenclamide, on insulin sensitivity, glycaemic control, and lipids in patients with Type 2 diabetes.

METHODS

Patients with Type 2 diabetes were randomized to receive either pioglitazone (initially 30 mg QD, n = 91) or micronized glibenclamide (initially 1.75 mg QD, n = 109) as monotherapy. Doses were titrated (to 45 mg for pioglitazone and 10.5 mg for glibenclamide) to achieve glycaemic targets during the next 12 weeks: fasting blood glucose of < or = 7 mmol/l and 1-h postprandial blood glucose of < or = 10 mmol/l. Patients were maintained on the titrated dose for 40 weeks.

RESULTS

Pioglitazone significantly increased insulin sensitivity compared with glibenclamide, as assessed by homeostasis model assessment (17.0% vs. -13.0%; P < 0.001), quantitative insulin sensitivity check index (0.011 vs. -0.007; P < 0.001) and fasting serum insulin (-1.3 pmol/l vs. 23.8 pmol/l; P = 0.007). The glibenclamide group had significantly lower HbA1c than the pioglitazone group after 12 weeks of therapy (7.8% vs. 8.3%, P = 0.015), but significantly higher HbA1c after 52 weeks of therapy (7.8% vs. 7.2%, P = 0.001). Pioglitazone significantly (vs. glibenclamide) increased mean HDL-C (P < 0.001), decreased mean triglycerides (P = 0.019), and decreased mean atherogenic index of plasma (AIP; P = 0.001) and mean total cholesterol/HDL-C (P = 0.004), without significantly elevating mean total cholesterol or mean LDL-C compared with glibenclamide. CONCLUSIONS These data suggest that the effects of pioglitazone are more sustained than those of glibenclamide for improving insulin sensitivity in patients with Type 2 diabetes, and that 52 weeks' treatment with pioglitazone has favourable effects on glycaemic control and lipoprotein profile.

Functional significance of the activation-associated receptors CD25 and CD69 on human NK-cells and NK-like T-cells

The application of autologous ex-vivo expanded cytotoxic lymphocytes to cancer patients may help to control minimal residual disease. However, the number of effector cells and the resulting antitumoral activity that can be generated in vitro are remarkably variable. Thus, we separately assessed the proliferative and cytotoxic potential of CD56+ CD3- natural killer (NK) and CD56+ CD3+ T-cells in relation to their expression of CD25, CD69, and CD16 in vitro. Two-week lymphocyte cultures from peripheral blood (n = 51) and from G-CSF-mobilized progenitor cell harvests (n = 11) were performed repeatedly from 14 women with breast cancer throughout conventional- and high-dose chemotherapy. A large proportion of CD25+ cells on day 7 of the culture predicted high expandability (r = 0.69, p < 0.00001), while elevated expression of CD69 predicted augmented cytotoxicity (r = 0.72; p = 0.00001) and low expandability (r = -0.69, p < 0.00001). CD25 and CD69 expression were inversely correlated (r = -0.8, p < 0.0001). CD16 expression was not suited to predict functional properties. Additionally, NK-cells were sorted by FACS according to CD25 versus CD69 expression. In a [3H]thymidine incorporation assay the CD25+ NK-cell fraction exhibited a higher proliferation rate than did the CD69+ fraction in all of three experiments. Together, our data suggest that CD69 is a useful marker for cytotoxic activity of NK cells, whereas proliferative potential is indicated by CD25 expression. These findings should help optimizing the ex-vivo generation of large numbers of cytotoxic effector cells for immunotherapy.

Expansion of mobilized peripheral blood progenitor cells under defined culture conditions rsing CD34+CD71-CD45- cells as a starting population

A major goal of experimental and clinical hematology is the identification of mechanisms and conditions supporting the expansion of transplantable hematopoietic stem cells. We assessed the expansion potential of CD34+CD71-CD45- cells derived from granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood under recently defined serum-free culture conditions. The CD34+CD71-CD45- cells in mobilized peripheral blood were found to contain the majority (92%+/-5.6) of primitive long-term culture initiating cells (LTCIC) and 53.5%+/-16.7 of the more committed colony-forming cells (CFC). Furthermore, this population represents 23.3%+/-4.1 of the total CD34+ cells and allows reduction of the cell density important for maintenance/expansion of primitive progenitor cells. CD34+ CD71- CD45- cells were cultured in defined serum-free media supplemented with 300 ng each of Flt-3 ligand and stem cell factor (SCF), 60 ng of interleukin (IL)-3, and 20 ng each of IL-6 and G-CSF. Mononuclear cells (MNC) and CFC were expanded 50-fold and 200-fold, respectively; primitive progenitor cells (LTC-IC) were maintained at input values after a total of 10 days of expansion. The addition of IL-15 to our cytokine cocktail expanded LTC-IC 2- to 3-fold and CFC to >500-fold. The data presented should allow clinical manipulation (purging) and expansion procedures with mobilized PBPC harvests without the loss of primitive progenitor cells and could be made applicable for large-scale clinical expansion.

Endogenous retroviruses and MS: using ERVs as disease markers

Multiple sclerosis (MS) has an unknown cause, but its epidemiology suggests an interplay between environmental factors, possibly including viruses, and genetic components. Endogenous retroviruses (ERVs) are elements of the human genome that potentially may act as either genetic markers for polymorphisms related to MS, or markers of environmental/endogenous stress. Activation of the ERVs HERV-H/RGH, HERV-W and ERV-9 was reported when specific cell types (mainly B cells) from MS patients were cultivated in vitro. Viral RNA from these ERVs has been detected by reverse-transcriptase polymerase chain reaction in sera/plasma and brain tissues from MS patients, although not exclusively from these patients. ERVs play unknown roles in MS: their activation may represent an inflammatory cytokine-mediated epiphenomenon; alternatively, preliminary evidence suggests that specific ERVs may act as auto-, super- or neoantigens with the potential to enhance inflammatory responses or induce autoimmune reactions. ERVs that occur in few copies in the human genome (e.g. ERV-3 and human endogenous retrovirus, HRES-1) may show polymorphic patterns in MS. Studies show that the sequences encoding the envelope protein of ERV-3 are polymorphic to a degree where it becomes impossible to link them with MS. In contrast, the HRES-1 long terminal repeat sequence has a polymorphic pattern with haplotypes characteristic of MS. Haplotypes from non-MS control groups were identical between different topographic areas, but haplotypes from MS patients were different, depending on the population.

Gender differences in the impact of adolescent smoking on lung function and respiratory symptoms. the Nord-Trøndelag Health Study, Norway, 1995-1997

Girls take up smoking at least as frequently as boys. Few studies have focused on gender differences in the impact of adolescent smoking. We evaluated the sex-specific effect of adolescent smoking on respiratory symptoms and lung function. All students in junior high and high schools in Nord-Trøndelag County Norway, 1995-97, were invited to participate in a cross-sectional study. Information on smoking habits and respiratory symptoms was obtained by self-administered questionnaires. Spirometry was performed in accordance with ATS standards. Eight-thousand-three-hundred and five students (83%) completed both questionnaire and spirometry. Among 6811 students aged 13-18 years (50.3% girls) with no history of asthma, 2993 (43.9%) reported never smoking, 665 (98%) reported occasional smoking, and 667 (9.9%) reported daily smoking (mean initiation age: 13.9 years). More boys than girls were heavy smokers. In all smoking categories, smokers reported a higher prevalence of respiratory symptoms than nonsmokers; symptoms increased with smoke burden. Girls reported more symptoms compared to boys with comparable smoke burden. A dose-response relation between smoking and reduced lung function was found only in girls. Girls were more vulnerable than boys to the impact of smoking on respiratory symptoms and lung function.

Breaking the rules? X-ray examination of hematopoietic stem cell grafts at international airports

Hematopoietic stem cell grafts from unrelated donors are commonly transported by aircraft. They must not be subjected to x-rays during security checks, which may cause inconvenient discussions between the courier and the airport security staff. We exposed hematopoietic stem cells from mobilized peripheral blood to a widely used x-ray hand-luggage control system. Cell viability as well as growth in vitro of mature progenitor cells (colony-forming cells), primitive progenitor cells (long-term culture-initiating cells), and lymphocytes were not altered even after 10 passages through the hand-luggage control system. Thus, repeated exposure to the low radiation dose of hand-luggage control systems (1.5 +/- 0.6 microSv per exposure) seems to be harmless for hematopoietic stem cells, which should simplify the international transport of stem cell grafts.

Physical exercise, sports, and lung function in smoking versus nonsmoking adolescents

Associations between adolescent smoking habits and exercise, particularly participation in sports and lung function were studied. All students aged 13-19 yrs in Nord-Trøndelag County, Norway, 1995-1997, were invited to join a cross-sectional study. Information on smoking habits and exercise was obtained by self-administered questionnaire. Spirometry was performed in accordance with American Thoracic Society standards. Of the 6,811 students (aged 13-18 yrs, without asthma), 2,993 (44%) reported never-smoking, and 1,342 (20%) reported current smoking (90% daily). Frequency of physical exercise was inversely associated with smoking, but participants in individual sports with lesser endurance, especially body-building and fighting sports, were more likely to be daily smokers than nonparticipants. Both daily (53%) and occasional smokers (43%) were more likely to have quit sports than never-smokers (26%)). Never-smokers showed a positive dose-response between physical exercise and lung function (forced vital capacity and forced expiratory volume in one second, adjusted for age and height). No similar significant association was observed in daily smokers. These data suggest that smoking habits in different sports should be considered when promoting physical activity as smoking prevention, and sports organizations should include smoking prevention programmes. Adolescents with better lung function may self-select into sports; this possibility needs to be studied in a longitudinal design.

Circulating cytotoxic CD8(+) CD28(-) T cells in ankylosing spondylitis

Circulating CD8(+) CD28(-) T cells were found to be expanded more in patients with ankylosing spondylitis than in an age-matched healthy population (41.2 +/- 17.7% versus 18.6 +/- 7.6%). The level of CD8(+)CD28(-) T cells was dependent on the disease status, but was independent of age. Most of the CD8(+) CD28(-) T cells produced perforin after stimulation in vitro, in contrast to their CD8(+)CD28(+) counterparts. From the clinical perspective, the percentage of the cytotoxic CD8(+) CD28(-) T cells reflected a more severe course of disease, as it correlated with distinct movement restrictions, as well as the metrology score summarizing cervical rotation (in sitting position), chin-to-jugulum distance, thoracic Schober, chest expansion, and fingers-to-floor distance (P = 0.032).

Photosynthetic water oxidation in Synechocystis sp. PCC6803: mutations D1-E189K, R and Q are without influence on electron transfer at the donor side of photosystem II

The oxygen-evolving manganese cluster (OEC) of photosynthesis is oxidised by the photochemically generated primary oxidant (P(+*)(680)) of photosystem II via a tyrosine residue (Y(Z), Tyr161 on the D1 subunit of Synechocystis sp. PCC6803). The redox span between these components is rather small and probably tuned by protonic equilibria. The very efficient electron transfer from Y(Z) to P(+*)(680) in nanoseconds requires the intactness of a hydrogen bonded network involving Y(Z), D1-His190, and presumably D1-Glu189. We studied photosystem II core particles from photoautotrophic mutants where the residue D1-E189 was replaced by glutamine, arginine and lysine which were expected to electrostatically differ from the glutamate in the wild-type (WT). Surprisingly, the rates of electron transfer from Y(Z) to P(+*)(680) as well as from the OEC to Y(ox)(Z) were the same as in the WT. With the generally assumed proximity between D1-His190 (and thus D1-Glu189) and Y(Z), the lack of any influence on the electron transfer around Y(Z) straightforwardly implies a strongly hydrophobic environment forcing Glu (acid) and Lys, Arg (basic) at position D1-189 into electro-neutrality. As one alternative, D1-Glu189 could be located at such a large distance from the OEC, Y(Z) and P(+*)(680) that a charge on D1-189X does not influence the electron transfer. This seems less likely in the light of the drastic influence of its direct neighbour, D1-His190, on Y(Z) function. Another alternative is that D1-Glu189 is negatively charged, but is located in a cluster of acid/base groups that compensates for an alteration of charge at position 189, leaving the overall net charge unchanged in the Gln, Lys, and Arg mutants.

[Experimental examination for optimized stabilisation of trochanteric femur fractures, intra- or extramedullary implant localisation and influence of femur neck component profile on cut-out risk]

INTRODUCTION

Fractures of the proximal femur are typical injuries of the elderly. Therefore immediate restoration of weight-bearing capacity and prevention of local complications with the need for of secondary surgical procedures are very important.

METHODS

In an experimental test the weight-bearing capacity under alternating load up to 2,000 N and 4,000 cycles was analysed in the newest implants for extramedullary fixation (the DHS with lateral buttress plate, DHS) and for intramedullary fixation (the gliding nail, GN). If no instability occurred a static maximum load test was performed. To avoid the influence of other variables the tests were performed with sowbone femora with A2, A31, (AO classification) subtrochanteric reversed and subtrochanteric transverse osteotomies. To analyse the influence of long term alternating load and of the biological bone, a pair of cadaver femora were tested with 100,000 cycles of 2,000 N alternating load after GN and DHS osteosynthesis. In a second examination the influence of the profile of the femur neck component on the migration and cut-out risk was tested. Nine head and neck parts of sowbone femora with a A2 osteotomy 1,000 alternating load tests at 1,000 and 1,500 N were performed after GN I beam plate, gamma nail and PFN screw fixation. Additionally, three pairs of cadaver femora were tested with 6,000 cycles from 1,000-3,500 N of alternating load comparing GN vs gamma, GN vs PFN and gamma vs PFN to avoid influence of the biological variability on the ranking.

RESULTS

The weight-bearing capacity of the GN (4,230-5,557 N) was about 100% higher than that of the DHS (2,465-3,049 N). The total deformation was 1/3 higher for the DHS (17.3 +/- 2.06 mm) than for the GN (10.73 +/- 4,33 mm). After 100,000 alternating load cycles no instability and a total deformation of 13.3 mm was found for the GN, but for the DHS instability occurred after 15,800 cycles. The migration of the I-beam GN plate at 1,000 N in sowbone femora was 0.7 mm for the gamma screw 1.69 mm and for the PFN 2 mm but one cut-out was observed. At 1,500 N the difference are even higher, all three PFN showed a cut-out and in two of the three gamma screws rotation of the head and neck around the screw was observed. In the cadaver tests similar differences were found with a migration at least double that of the GN I beam plate for the gamma screw and the PFN double-screw fixation. There was no difference between the gamma and PFN fixation in the cadaver pair test.

Optimal timing for the collection and in vitro expansion of cytotoxic CD56(+) lymphocytes from patients undergoing autologous peripheral blood stem cell transplantation

To identify the optimal time for the collection of CD56(+) cytotoxic lymphocytes for adoptive immunotherapy in patients undergoing high-dose chemotherapy (HDCT) and peripheral blood stem cell (PBSC) transplantation, 18 breast cancer patients receiving either three cycles of epirubicin/paclitaxel (CT x 3) followed by HDCT and PBSC transplantation (n = 12) or CTx6 (n = 6) were studied. Blood samples were obtained before each CT/HDCT cycle, from PBSC collections, and repeatedly after autografting for up to 12 months. The number of CD56(+)3(-) and CD56(+)3(+) lymphocytes, their in vitro expandability with interleukin-2, and their cytotoxicity against MCF-7 and Daudi cells were analyzed. Six healthy females served as controls. CD56(+) cell counts in both treatment groups were subnormal but stable during the observation period. The cytotoxicity of the expanded CD56(+) cells was normal and unaffected by the treatment. The in vitro CD56(+) cell expandability (controls, 100 +/- 31-fold, mean +/- SEM) was normal before CT1 and CT2, but reduced in PBSC harvests performed after CT2 and application of G-CSF (21 +/- 6-fold; p < 0.01). After PBSC harvesting, the CD56(+) cell expandability increased to 185 +/- 74-fold and 170 +/- 69-fold (before CT3 and HDCT). This increase was not observed in those patients who did not undergo PBSC mobilization. Two weeks after autografting, the CD56(+) cell expandability was minimal (6 +/- 1-fold), and recovered to 34 +/- 6-fold. Thus, CT, HDCT and autografting do not alter the frequency and inducible cytotoxicity of CD56(+) cells in breast cancer patients. However, the proliferative capacity of CD56(+) cells obtained from PBSC harvests and after autografting is impaired. Therefore, instead of the PBSC graft, maximally expandable CD56(+) cells obtained at least 1 week after PBSC collection should be considered for adoptive immunotherapy after PBSC autografting.

[Palliative immunotherapy of cancer]

In addition to surgery, chemotherapy and radiation, immunotherapy of cancer resembles a potential treatment strategy for patients with cancer. To strengthen the immune system might help to control or even to eradicate malignant tumors. Immunoaugmentative strategies include biological response modifiers as interferons and interleukins. Recently, monoclonal antibodies directed against tumor associated antigens and coupled with radioisotopes or cytotoxic agents have become available. Adoptive immunotherapy uses immune effector cells, i.e. T-cells or natural-killer cells that are activated in-vitro by appropriate cytokines. Dendritic cells, either unstimulated or pulsed with tumor derived molecules have shown promising anticancer activity in selected tumors. Immunonutrition, that is the manipulation of immune phenomenons through edibles is a new and interesting topic. Immunologic strategies for the treatment of malignant diseases are currently under intensive preclinical and clinical investigation. Further insights into the mechanisms of host-defense against cancer cells and the modification of immune-effector cells might pave the way to efficient treatment strategies, even in the palliative setting.

Additive effect of the HLA-DR15 haplotype on susceptibility to multiple sclerosis

Multiple sclerosis (MS) has been associated with the human leukocyte antigen DR15 allele in Caucasians of North and Central European origin. However, the relative effect of the DR15 homozygous and the DR15 heterozygous genotypes on the disease susceptibility is unclear. Based upon results from three North European studies we have examined this by meta-analysis. Our results suggested that the effect of the DRB1*1501,DQA1*0102,DQB1*0602 haplotype on the susceptibility to MS is additive, perhaps reflecting that development of the disease is facilitated by a high density surface expression of the antigen presenting molecules encoded by this haplotype. Possible implications of our finding to future studies of the genetic background of MS is discussed.

Genetic susceptibility to multiple sclerosis: detection of polymorphic nucleotides and an intron in the 3' untranslated region of the major histocompatibility complex class II transactivator gene

The master player in the transcriptional regulation of major histocompatibility (MHC) class II genes is a factor known as the MHC class II transactivator (CIITA). In this study we searched for polymorphisms in the 5' and 3' ends of the human CIITA gene to assess whether or not there is an association between alleles of this gene and multiple sclerosis (MS). Polymorphism screening based upon detection of single strand conformational changes (SSCP analysis) followed by sequencing revealed six single nucleotide variations, namely one in the promoter utilized by B cells and five in the 3' untranslated region (UTR) of the gene. Determination of alleles at these polymorphic sites was facilitated by treatment of amplified DNA fragments with a panel of appropriate restriction enzymes. The distributions of CIITA alleles did not differ between MS patients and control subjects (p > 0.05). After subgrouping of the patients into relapsing-remitting MS and primary progressive MS we found that the distribution of promoter alleles in the latter of these two patient groups differed from that of healthy control subjects (p = 0.04). There was no evidence of linkage disequilibrium between the polymorphic site in the B cell specific promoter and those in the 3' UTR. Based upon the polymorphic sites in the 3' UTR we identified two common CIITA haplotypes which were present at similar frequencies in patients and control subjects. Assuming that susceptibility to MS depends upon type of MHC class II molecule as well as the amounts of expressed class II molecules we tested for interaction between DR15 status and CIITA alleles. No such interaction was detected. Unexpectedly, we identified an intron in the 3' UTR of the human as well as the mouse CIITA gene. Due to the proximity of these introns to the termination codon in both the human and mouse CIITA gene, the mechanism for regulation of transcript stability known as nonsense-mediated decay is probably not involved in the posttranscriptional control of the expression of these genes. So far, the function and significance of the intron in the human and mouse CIITA genes are unknown.