Polymorphism in the upstream regulatory region of the HLA-DQB1 gene in liver graft recipients

HLA-DQB1*0302 allele frequency is increased in liver graft recipients with acute rejection. We investigated polymorphism in the upstream regulatory regions (URRs) of the DQB1 gene to determine whether polymorphism in the DQB1 promoter region influences liver graft acceptance. A combination of typing protocols based on the polymerase chain reaction were used in 103 first-time liver transplants and 108 healthy Spanish controls. The QBP3.21 allele frequency and QBP3.21-DQB1*0302 haplotype were significantly different in recipients with acute rejection compared to those with good graft acceptance and to controls. Of major interest for acute rejection development are the promoter "splits" of DQB1*0302 (QBP3.21, QBP3.22, and QBP3.3 alleles), which are in linkage disequilibrium with DQB1*0302. The promoter splits were equally distributed in all groups. Thus, although there are significant differences in the frequencies of the QBP alleles and QBP-DQB1 haplotypes between recipients with and without acute rejection and controls, the composition of these haplotypes is essentially the same in all groups. In conclusion, our data show that the polymorphism in the DQB1 promoter region does not clearly influence liver graft acceptance, and, as occurs in other populations, QBP alleles exhibit strong linkage disequilibrium with the DQB1 locus.

Analysis of the phenotypic distribution of HLA class I and class II in atopic and non-atopic asthma patients

In several studies the HLA system has been implicated in the development of asthma, but the importance of the associations between HLA genes and asthma remains unclear. The aim of this study was to determine the HLA class I and II phenotypic frequencies in a population of asthmatics, and to analyse the relationship between these phenotypes and any type of asthma. We typed HLA class I and II antigens in a series of 189 asthmatic individuals (102 atopic and 87 non-atopic), and in a control population of 150 unrelated healthy Caucasoid donors. When the HLA phenotypic frequencies were compared, no statistical differences were found. Therefore, no definitive HLA association could be established with atopic or non-atopic asthma in the studied population. Abbreviations AA, atopic asthma; FEV1, forced expiratory volume in 1 s; NAA, non-atopic asthma; PCR, polymerase chain reaction; SSOP, sequence-specific oligonucleotide probes; SPT, skin prick test.

Co-stimulation of cultured peripheral blood mononuclear cells from intrinsic asthmatics with exogenous recombinant IL-6 produce high levels of IL-4-dependent IgE

Asthma is an inflammatory airway disorder, traditionally subdivided into extrinsic, immunoglobulin E (IgE)-mediated, and intrinsic asthma of unknown aetiology. IgE synthesis requires contact between T- and B-cells and a signal provided by interleukin (IL)-4, which can be modulated by IL-6. The objective of this study was to evaluate the effects of IL-4 and IL-6 on total IgE synthesis by peripheral blood mononuclear cells from intrinsic and extrinsic asthmatics. Peripheral blood mononuclear cells from intrinsic and extrinsic asthmatic patients and from healthy subjects were cultured and stimulated with pokeweed mitogen, recombinant IL-4 and IL-6. The IgE level in serum and supernatants was measured by an enzyme-linked immunoassay. Serum IgE was significantly lower in intrinsic asthma than in extrinsic asthma, but significantly higher than in control subjects. IgE production by cultured mononuclear cells from extrinsic asthmatics was not modified after exogenous IL-4 and IL-6 addition. However, intrinsic asthmatics showed enhancement of IgE synthesis in response to IL-4 stimulation, reaching a threefold increase of the spontaneous IgE values, when simultaneous recombinant IL-4 plus IL-6 stimulus was used. Our results indicate that exogenous recombinant interleukin-6 can significantly upregulate the interleukin-4-dependent immunoglobulin E synthesis in intrinsic asthma. This suggests that immunoglobulin E could also play a role in the pathogenesis of intrinsic asthma, in which an interleukin-6 threshold would be critical.

Cytokine serum profiles in allergic and non-allergic asthma. Increased production of IL-10 by non-allergic asthmatic patients

Studies were undertaken to determine whether differences in serum cytokine balances could be involved in the pathogenesis of allergic and in non-allergic asthma. At this propose, interferon-gamma, tumor necrosis factor-alpha, interleukin-2, interleukin-4, interleukin-6, and interleukin-10 were measured by enzimoimmunoassay. The analysis was performed on 24 allergic and 24 non-allergic asthmatic patients and 16 healthy subjects. IFN-gamma and TNF-alpha, included into the type 1 cytokines, appeared significantly increased in the allergic with respect to the non-allergic asthmatic patients (p = 0.01) and (p < 0.001) respectively, while IL-10, which belongs to the type 2 cytokines, was significantly increased in the non-allergic asthmatic (p < 0.001). The IL-6 analysis did not show any significant difference in either of the study group. The most interesting finding was the high serum IL-10 values detected in intrinsic asthmatic patients, which in turn, suggests that this cytokine could participate in the regulation of different immunological features that occurs in non-allergic asthma, and maybe it could indicate a higher stimulated state of cells in this type of asthma. The data presented in this report show a different cytokine profile in serum from allergic and non-allergic asthmatic patients and denote a stronger prevalence of type 2 cytokines in intrinsic asthma.