Clonal dysregulation of the antibody response to tetanus-toxoid after bone marrow transplantation

After bone marrow transplantation (BMT), a prolonged dysregulation of humoral immunity can be observed. In the present study, we investigated whether this is reflected in an abnormal production of specific antibodies (Ab) to the T-cell-dependent recall antigen tetanus-toxoid (TT). The study group consisted of children receiving transplants of an unmodified allogeneic graft and of adults receiving either a T-cell- depleted allogeneic or an unmodified autologous BM graft. Findings were compared with those in healthy controls. In pediatric graft recipients, who were routinely revaccinated early after BMT, the Ab response was quantitatively superior to that in adult graft recipients who did not receive early revaccination. In the majority of graft recipients, the time period after vaccination required to reach the peak level of antibodies was prolonged and the number of responding TT-specific B- cell clones was markedly decreased in comparison with controls. In controls, a low frequency of dominant B-cell clones may produce low quantities of homogeneous Ab components (H-Ab) against a heterogeneous background. However, in BM graft recipients, "overshooting" of Ab production by separate B-cell clones was observed, resulting in the development of H-Ab at a relatively high concentration. These abnormalities were present up to 10 years after BMT, irrespective of either the age of the recipient, the modulation of the graft, or the vaccination schedule used. It is hypothesized that the dysregulated Ab production is the consequence of activation of a restricted number of resting memory B cells, present in germinal centers, repopulating gradually after BMT. Our data show that routine revaccination early after BMT improves the humoral immune response. However, because of a clonally dysregulated Ab production, long-lasting qualitative defects may be present even after normalization of Ab titers.     

Association of mannose-binding lectin genotype with cardiovascular abnormalities in Kawasaki disease

Kawasaki disease is an acute vasculitis of possible infectious cause, which in particular affects the coronary arteries. Young children rely mostly on their innate immune system for protection against invading microorganisms, of which mannose-binding lectin is an important component. We aimed to investigate the possible role of the gene for this molecule (MBL) in white Dutch patients with Kawasaki disease. In 90 patients, frequency of mutations in the MBL gene was higher than in healthy children. In children younger than 1 year, those with mutations were at higher risk of development of coronary artery lesions than were those without (odds ratio 15.7, 95% CI 1.4-176.5, p=0.026). Our findings suggest that the innate immune system contributes differently to pathophysiology of Kawasaki disease at various ages.     

Helicobacter species are not detectable by 16S rDNA PCR in bile from Dutch patients with common bile duct stones

BACKGROUND: Some Helicobacter species colonize the intestinal tract. To explore the possible relation between Helicobacter spp. and gallbladder disorders, we have investigated their presence in bile of patients with biliary obstruction and dilatation of the bile ducts. METHODS: Bile was sampled from 31 Dutch patients with biliary obstruction identified by jaundice and dilatation of the bile ducts on ultrasound. Samples (n = 31) were obtained immediately following cannulation of the common bile duct (CBD) by endoscopic retrograde cholangiopancreatography (ERCP) (n = 29) or by peri-operative puncture of the gallbladder (n = 2). DNA was isolated from bile by binding to diatoms. Helicobacter spp. were detected by a sensitive (detection limit 1 CFU per reaction tube) 16S rDNA PCR with genus-specific primers. Duplicate samples were spiked with Helicobacter pylori DNA and subjected to PCR in order to check for inhibition. RESULTS: 28 patients had CBD stones (bile collected by ERCP (n = 26) or operatively (n = 2)), 2 had a pancreatic head tumor, and in 1 no abnormalities were found. In 1 of 21 amplifiable bile samples (10/31 inhibited) from Dutch patients with CBD stones, H. pylori 16S rDNA was found. CONCLUSION: Our data indicate that CBD stones in Dutch patients are not associated with the presence of Helicobacter spp. in bile.     

In through the out door: serology for atrophic gastritis

Gastric cancer remains the second biggest cause of cancer death worldwide. The most common type of gastric cancer, the intestinal type, is usually preceded by chronic atrophic gastritis. Gastritis serology is therefore of crucial importance for population-based screening and prevention studies. Helicobacter pylori serum antibodies can adequately diagnose inflammation of the gastric mucosa, but the serological diagnosis of atrophic gastritis is more hazardous. Many tests have been used for this purpose, either alone or in various combinations. Depending on the population, pepsinogens and gastrin often have a high specificity but low sensitivity for the diagnosis of atrophic gastritis, whereas antibodies against H. pylori or CagA have a high sensitivity but low specificity. A combination of two tests, e.g. H. pylori antibodies and pepsinogen I, may balance this issue and provide adequate screening tools, although there is a clear need for further improvement and simplification of serological testing for atrophic gastritis.     

Renal Function and Bone Loss in a Cohort of Afro‐Caribbean Men

Poor renal function is associated with increased rates of bone loss and osteoporotic fractures in Caucasian men. The importance of kidney function for skeletal health in African ancestry men, who are a population segment with a high prevalence of chronic kidney disease as well as high peak bone mass, is not well known. We examined the relationship between estimated glomerular filtration rate (eGFR) and rates of bone loss in a large population cohort of otherwise healthy Afro‐Caribbean men aged 40 years and older. Dual X‐ray absorptiometry of the proximal femur and quantitative computed tomography of the proximal radius and tibia were obtained approximately 6 years apart. We calculated eGFR from serum creatinine that was measured in fasting samples in 1451 men. Impaired kidney function (IKF, eGFR<60 ml/min/1.7 m²) was observed in 8.6% of the cohort. The relationship between IKF and baseline BMD and annualized rate of change in BMD was analyzed controlling for potentially important confounders. IKF was not associated with baseline BMD. In contrast, men with IKF experienced a rate of decline in areal BMD at the total hip, femoral neck and trochanter and cortical volumetric BMD compared to those with normal kidney function (p<0.05 for all). Impaired kidney function was not associated with changes in trabecular volumetric BMD. In conclusion, poorer kidney function is associated with accelerated bone loss among otherwise healthy Afro‐Caribbean men even after controlling for age and other important medical and lifestyle related variables. © 2015 American Society for Bone and Mineral Research.     

Antiidiotypic IgG crossreactive with Rh alloantibodies in red cell autoimmunity

IgG autoantibodies eluted from RBCs of antiglobulin positive normal blood donors contained at least two antibody populations, an IgG autoantibody (Ab 1), and an IgG population (Ab 2) that agglutinated RBCs coated with some Rh(D) alloantibodies. Eight of 24 autoantibody eluates tested agglutinated 3 of 10 anti-Rh(D) sensitized RBCs. The agglutinating activity was inhibited specifically by preincubation of the autoantibody eluate with the reactive anti-D. The reaction did not require the Fc domain of the anti-Rh(D), since autoantibody eluates agglutinated RBCs coated with F(ab')2 prepared from the reactive anti-D sera. These findings indicate that the RBCs of some antiglobulin- positive blood donors contain an immunoglobulin auto-antiidiotype (Ab 2) against the RBC autoantibody (Ab 1) which is demonstrable through its cross-reactivity with selected Rh(D) alloantibodies. Identification of auto-antiidiotypes in RBC autoimmunity lends support to the idiotype- antiidiotype network hypothesis of immune regulation and is consistent with the bizarre and complex serology of autoimmune hemolytic anemia. The absence of clinical hemolysis in antiglobulin-positive normal blood donors suggests that immunoglobulin idiotype-antiidiotype interactions may play a role in modulating the effects of RBC autoimmunity.     

Hemostatic plug formation in normal and von Willebrand pigs: the effect of the administration of cryoprecipitate and a monoclonal antibody to Willebrand factor

Hemostatic plug (HP) formation was investigated in the ear bleeding time incision in normal and von Willebrand pigs. HP volume was calculated by integrating the areas of serial sections. In normal pigs (n = 11), platelets immediately formed a layer on the surface of the cut channel. Platelet aggregates formed at the ends of transected vessels and gradually enlarged. Finally, all transected vessels were occluded by HP and bleeding stopped. In contrast, large HPs were formed in the incision in von Willebrand's disease (vWD) pigs (n = 4); these HPs did not cover the ends of the transected vessels, which continued to bleed, allowing the formation of large hemostatically ineffective platelet aggregates in the incision. Canals traversed these HPs, and bleeding from the open vessels may have continued through them. After infusion of cryoprecipitate into a vWD pig, the bleeding time shortened, and the morphological findings of the HPs were similar to those of normal pigs. In normal pigs (n = 3) infused with an anti- Willebrand factor monoclonal antibody, which prolonged the bleeding time, a large HP formed in the incision, similar to that observed in the vWD pig. The volume of the normal and vWD HPs increased with time. These in vivo findings suggest that Willebrand factor is involved in the localization of the HP to the damaged vessel and may also play a role in platelet-platelet interaction. A computerized morphometric technique was used for measuring the volume of the hemostatic plugs and the distance of sequential points on the perimeter of the HP from the center of selected bleeding vessels.     

The major histocompatibility complex region marked by HSP70-1 and HSP70- 2 variants is associated with clozapine-induced agranulocytosis in two different ethnic groups

Genes of the major histocompatibility complex (MHC) have been associated with susceptibility to drug-induced adverse reactions. We previously found that clozapine-induced agranulocytosis (CA) is associated with the HLA-DRB1*0402, DRB4*0101, DQB1*0302, DQA1*0301 haplotype in Ashkenazi Jewish patients and with the HLA-DRB1*1601, DRB5*02, DQB1*0502, DQA1*0102 haplotype in non-Jewish patients. In the present study, we tested the hypothesis that the variants of the heat- shock protein 70 (HSP-70) encoded by the HSP-70 loci located within the MHC region and known to be involved in apoptosis and regulation of cell proliferation could play an important role in molecular mechanisms of CA. First, we analyzed HSP70-2 polymorphism in risk-associated haplotypes from HLA homozygous cells and normal individuals and confirmed that the HSP70-2 9-kb variant was associated invariably with DR4 (HLA-DRB1*0402, DQB1*0302) and DR2 (HLA-DRB1*01601, DQB1*0502, DQA1*0102 and HLA-DRB1*1501, DQB1*0602) haplotypes, which were the haplotypes found increased in Jewish and non-Jewish patients with CA, respectively. The 9.0-kb variant was also found to be associated with HLA-B44, DRB1*0401 and HLA-B44, DRB1*07 haplotypes. Second, in patients with CA (12 Ashkenazi Jewish and 20 non-Jewish patients), HSP70-1 A and HSP70-2 9.0-kb variants were associated with the MHC haplotypes found by us to be markers of susceptibility to CA. The clozapine-treated control group had an excess number of HSP70-1 C and HSP70-2 8.5-kb variants, consistent with genetic resistance to CA associated with those variants. This finding supports our hypothesis that a dominant gene within the MHC region (marked by HSP70-1 and HSP70-2), but not necessarily HLA, is associated with CA in two different ethnic groups.