Distribution of MICA alleles and haplotypes associated with HLA-B in Greek population.

INTRODUCTION: The Major Histocompatibility Complex Class I-related chain A gene (MICA) is a highly polymorphic functional gene located close to the HLA-B locus. Certain MICA alleles have been related to inflammatory and autoimmune diseases while MICA antibodies have been implicated in organ allograft rejection or graft-versus-host disease (GVHD). AIM: The aim of this study was to identify the frequencies of MICA alleles and MICA ~ HLA-B haplotypes in the Greek population since, as far as we know, these data are still limited. METHODS: DNA was obtained from 277 unrelated healthy Greek individuals of Caucasian origin, volunteer donors of blood stem cells. HLA-B* and MICA* genotyping was performed by reverse PCR-SSOP. RESULTS: A total of 18 MICA alleles were defined in the present study. The five most frequent alleles in the Greek population were MICA*008 (24.6%), MICA*009 (22.36%), MICA*018 (16.03%), MICA*002 (8.02%) and MICA*004 (7.17%) which altogether account for 77.8% of all alleles. The most common MICA ~ HLA-B haplotypes were MICA*018 ~ B*18 (12.5%) and MICA*009 ~ B*51(11.5%). CONCLUSIONS: The five most frequent MICA alleles in the Greek population were *008, *009, *018, *002, *004. In other Caucasian populations, two of these alleles (*008, and *004) were observed in similar frequencies. MICA*002 was observed less frequently (8.02%) in the Greek population compared to other Caucasian groups (frequencies > 15%). Also, MICA*009 and MICA*018 had elevated frequencies (above 15%) whereas in other Caucasian populations they were found around 10% or less. These data may be important for the elucidation of the role that MICA polymorphisms play in organ and stem cell transplantation and to identify the relation of certain MICA with susceptibility to specific diseases.

The role of the immunogenetic background in the development and recurrence of acute idiopathic pericarditis.

OBJECTIVES: We assessed the role of the immunogenetic background in the development and recurrence of acute idiopathic pericarditis (AIP). METHODS: Fifty-five patients with a first episode of AIP were followed for 23.8 ± 6.3 months and recurrences were recorded. The control group consisted of 246 healthy individuals. In all subjects, genomic human leukocyte antigen (HLA) typing was performed. Moreover, circulating lymphocyte subpopulations were studied in 44 randomly selected patients and in 20 controls. RESULTS: An increased frequency of HLA-A*02, -Cw*07 and -DQB1*0202 alleles, and a decreased frequency of the -DQB1*0302 allele was detected in patients with AIP. The recurrence rate was 40% and time to recurrence was 202.8 ± 164.1 days. In patients with idiopathic recurrent pericarditis (RP), increased frequencies of HLA-A*02, -Cw*07 and -DQB1*0202 alleles were found. Notably, no patient with RP exhibited HLA-DRB1*04 and -DQB1*0302 alleles. Patients with RP exhibited lower CD4+/CD45RA+ naïve T cells (p = 0.03) than controls, and higher CD8+DR+ activated T cells (p = 0.01) than patients without recurrence and controls. CONCLUSIONS: HLA alleles may confer either susceptibility or resistance to AIP and RP. Circulating T-cell subpopulations may also predict RP. A combination of the above parameters might help to better define patients prone to recurrence.

Early initiation of cannabis use: a cross-national European perspective.

PURPOSE: To examine the relationship of the early initiation of cannabis use with other high risk behaviors and with psychosocial and health-related correlates in 15-year-old adolescents in six European countries. METHODS: This study reports on nationwide cross-sectional surveys in six European countries in 2001-2002, within the framework of the World Health Organization's collaborative study, Health Behaviour in School-aged Children (HBSC). Data were collected through anonymous questionnaires self-completed in classrooms. Descriptive and multivariate analyses were used to assess differences between countries in age of first cannabis use and associations with health and related psychosocial variables. RESULTS: The prevalences of lifetime and last-year cannabis use ranged from 30.7% and 27.5%, respectively, in the Czech Republic, to 5.4% and 4.1%, respectively, in Greece. Age at first use was lower in the high prevalence countries than in countries with lower prevalence. For 15-year-olds, frequent use of tobacco and alcohol and other risk behaviors were correlated with early (13-15 years old) and especially very early (< or = 13 years old) cannabis initiation. CONCLUSIONS: Although different patterns of prevalence and age of initiation were observed between participating countries, early cannabis use was almost uniformly associated with higher odds of more frequent use of cannabis and other substances, and with a common set of other problems. Our findings suggest that prevention of drug abuse must commence in preadolescence.