The proliferative T-lymphocyte response to streptokinase

Purified streptokinase was found to initiate a proliferative T-lymphocyte response. The response was characterized by dose-response and kinetics investigations. Streptokinase did not initiate any response when tested on T lymphocytes from newborns, thus indicating that the proliferative T-lymphocyte response to streptokinase in vitro is an antigen stimulated activation of T lymphocytes from individuals previously sensitized in vivo. Of healthy individuals, 40% (16 out of 40 tested) showed a significant proliferative response to streptokinase. Methylprednisolone, cyclosporin A, theophyllamine and verapamil all inhibited the streptokinase-stimulated proliferative T-lymphocyte responses in a dose-dependent manner.     

Susceptibility to develop celiac disease is primarily associated with HLA-DQ alleles

We have recently reported that the susceptibility to develop celiac disease (CD) seems to be primarily associated to a particular combination of an HLA-DQA1 (DQA1*0501) and an HLA-DQB1 (DQB1*0201) allele: i.e., a particular DQ alpha/beta heterodimer. To investigate whether certain DP alleles might also contribute to the genetic susceptibility, DPA1 and DPB1 genes of 94 CD patients and 132 healthy controls were examined by probing in vitro amplified DNA with sequence-specific oligonucleotide probes corresponding to all hitherto known DPA1 and DPB1 alleles. The frequencies of the DPA1*0201 and of the DPB1*0101 alleles were increased in CD patients compared to healthy controls (0.31 versus 0.14 and 0.25 versus 0.08, respectively). However, these DP alleles were in linkage disequilibrium with CD-associated DQ alleles in the normal population, and the difference in frequency of these DP alleles was no longer significant when CD patients and healthy controls carrying the CD-associated DQA1*0501 and DQB1*0201 alleles were compared. DQB1*0201 homozygous individuals were overrepresented among DQB1*0201-positive patients compared to controls. When DQB1*0201 heterozygous patients and controls were compared, nearly identical frequencies of the DPA1*0201 and the DPB1*0101 alleles were found. Thus, the observed increase of the DPA1*0201 and DPB1*0101 alleles among CD patients seems mainly to be caused by linkage disequilibrium to the CD-associated DQ alleles.     

HLA-DR and -DQ genotypes of celiac disease patients serologically typed to be non-DR3 or non-DR5/7.

The susceptibility to develop celiac disease (CD) seems to be primarily associated to a particular HLA-DQ alpha/beta heterodimer encoded by the DQA1*0501 and DQB1*0201 alleles, in cis position on the DR3-DQ2 haplotype or in trans position by DR5-DQ7/DR7-DQ2 heterozygotes. However, exceptional patients exist who are neither DR3 nor DR5/DR7, particularly among Southern European populations. We therefore examined the DRB1, DQA1, and DQB1 alleles of 13 Spanish CD patients who were serologically typed to be neither DR3 nor DR5/DR7. Five patients were found to carry the DQA1*0501 and DQB1*0201 alleles either in cis or in trans position, three of them had previously been serologically mistyped. However, two of these patients carried DQA1*0501 and DQB1*0201 on haplotypes other than DR3 or DR5 in combination with DR7. One of the latter patients carried an unusual DR4-DQ2 haplotype, while another had an unusual DR8-DQ2 haplotype. Four of the remaining eight patients carried DR4-DQ8 haplotypes. Taken together, our findings provide further evidence that the DQ alpha/beta heterodimer encoded by the DQA1*0501 and the DQB1*0201 alleles confers the primary HLA-associated susceptibility to develop CD. However, our studies also corroborate that a second (and "weaker") HLA-associated CD susceptibility gene may be present on some DR4-carrying haplotypes.     

Genetic analysis of the CD28/CTLA4/ICOS (CELIAC3) region in coeliac disease

Abstract:  In order to extend our previous findings of genetic linkage to the CD28/CTLA4/ICOS region on chromosome 2q33 ( CELIAC3 ) in coeliac disease (CD), we have investigated 22 genetic markers in 325 Norwegian/Swedish multiplex and simplex CD families. We found both linkage and association with several markers, primarily in the multiplex material. We observed strong linkage disequilibrium (LD) between SNPs (Single Nucleotide Polymorphisms) within an LD block delimited by MH30 and D2S72. A haplotype of this region marked by the alleles −1147*T: + 49*A:CT60*G:CT61*A was significantly associated with CD, suggesting that one or more polymorphisms of this haplotype, possibly −1147*T, are involved in CD susceptibility. The CT60 SNP, a polymorphism found to be most strongly associated with some other immune-mediated diseases, was not associated with CD, as this SNP was part of both associated and non-associated haplotypes. Moreover, our results suggest that CELIAC3 harbours several independent loci contributing to CD susceptibility.     

Anti-PAD4 autoantibodies in rheumatoid arthritis: levels in serum over time and impact on PAD4 activity as measured with a small synthetic substrate

Isoform 4 of the human peptidylarginine deiminase (hPAD4) enzyme may be responsible for the citrullination of antigens in rheumatoid arthritis (RA) and has been shown to be itself the target of disease-specific autoantibodies. Here, we have tested whether the level of serum anti-hPAD4 antibodies in RA patients is stable over a period of 10 years and whether the antibodies influence hPAD4-mediated deimination of the small substrate N-α-Benzoyl-l-arginine ethyl ester. RA sera (n = 128) obtained at baseline and after 10 years were assessed for anti-hPAD4 antibodies by a specific immunoassay. For 118 RA patients, serum anti-hPAD4 IgG levels were stable over 10 years. Seven patients who were negative for anti-PAD4 IgG at baseline had become positive after 10 years. Further, total IgG from selected RA patients and controls were purified, and a fraction was depleted for anti-hPAD4 antibodies. Kinetic deimination assays were performed with total IgG and depleted fractions. The k _cat and K _m values of hPAD4-mediated deimination of N-α-Benzoyl-l-arginine ethyl ester were not affected by the depletion of the anti-hPAD4 antibodies from the total IgG pool. In conclusion, RA patients remain positive for anti-hPAD4 antibodies over time and some patients who are initially anti-hPAD4 negative become positive later in the disease course. The anti-hPAD4 antibodies did not affect the enzymatic activity of hPAD4 when the small substrate N-α-Benzoyl-l-arginine ethyl ester was used. However, this finding may not exclude an effect of these autoantibodies on citrullination of protein substrates in RA.     

Surface expression of transglutaminase 2 by dendritic cells and its potential role for uptake and presentation of gluten peptides to T cells

Celiac disease is a chronic small intestinal inflammation driven by gluten-reactive T cells of the intestinal mucosa. These T cells are HLA-DQ2 or -DQ8 restricted, and predominantly recognize gluten peptides that are deamidated by the enzyme transglutaminase 2 (TG2). Our recent results strongly suggest that duodenal CD11c(+) dendritic cells (DC) are directly involved in T cell activation in the celiac lesion. The aim of this study was to investigate whether surface-associated TG2 could be involved in receptor-mediated endocytosis of gluten peptides, a process that may contribute to the preferential recognition of deamidated peptides. We found that both monocyte-derived DC and local CD11c(+) DC in the duodenal mucosa expressed cell surface-associated TG2. As phenotypic characterization of CD11c(+) DC in the celiac lesion suggests that these cells may be derived from circulating monocytes, we used monocyte-derived DC in functional in vitro studies. Using a functional T cell assay, we obtained evidence that cell surface-associated TG2 is endocytosed by monocyte-derived DC. However, we were unable to obtain evidence for a role of surface TG2 in the loading and subsequent generation of deamidated gluten peptides in these cells.     

Intraepithelial lymphocytes in celiac disease: license to kill revealed

Infiltration of lymphocytes in the small intestinal epithelium is a hallmark of active celiac disease. In this issue of Immunity, two papers uncover mechanisms controlling the cytolytic potential of these cells and provide evidence that lymphocyte killing of enterocytes is an important part of the celiac disease pathogenesis.     

Pre- and inter-hospital transport of severely head-injured patients in rural Northern Norway

The purpose of this study was to survey the time consumed during the pre- and inter-hospital transport of severely head injured patients in Northern Norway. All patients (n = 85) operated for an intracranial mass lesions within 48 h after injury during the 10-year period 1986-1995 were included in this retrospective analysis. Ambulance records, transfer notes, and hospital records were reviewed. The transport of patients was classified as either direct from the trauma scene to the University Hospital (direct admission group) or as an inter-hospital transfer (transfer group). Forty-seven (55%) patients were in the direct admission group, and 38 (45%) were transferred through another hospital. The majority of patients (81%) were transported by air ambulance. Median time from injury to arrival in the emergency room was 5 (1-44) h. Time necessary for transport was significantly (p < 0.001) shorter in the direct admission group (median 3 h) compared to the transfer group (median 8 h). The inter-hospital transfer time was < or = 3 h in 17%. Clearly, the advanced air ambulance service in Northern Norway makes rapid inter-hospital transfer possible despite extremely long geographical distances. Our findings indicate that this possibility is not always utilized.