Regulation of delayed-type hypersensitivity IV. Antigen-specific suppressor cells for delayed-type hypersensitivity induced by lipopolysaccharide and sheep erythrocytes in mice.

Mice injected subcutaneously with 1 x 10(8) sheep red blood cells (SRBC) developed high levels of delayed-type hypersensitivity (DTH) to SRBC 4-8 days after injection. Such DTH was suppressed when 100 microgram lipopolysaccharide (LPS) was injected intravenously 1-2 days before or at the time of SRBC injection. This suppression of DTH was transferable by spleen, lymph node, thymus and bone marrow cells to sensitized or normal syngeneic recipients, but could not be transferred by serum. Suppressor cells were not induced by LPS alone or SRBC alone, and they were antigen-specific since DTH to chicken red blood cells was not affected. The suppressor cells appeared in the spleen in optimum number 3-4 days after induction. They were theta-negative and Ig-positive as judged by antiserum plus complement treatment and by Ig rosette separation. Attempts to obtain soluble suppressor factor from the suppressor cells by sonication or in vitro incubation were unsuccessful. Mitomycin C treatment of the suppressor cells completely abolished the suppressor activity. Thus, LPS, in conjunction with antigen, appears to induce a population of specific suppressor B cells which are capable of regulating T cell function.     

Large-scale screening of nasal swabs for Bacillus anthracis: descriptive summary and discussion of the National Institutes of Health's experience

In October 2001, a letter containing a large number of anthrax spores was sent through the Brentwood post office in Washington, D.C., to a United States Senate office on Capitol Hill, resulting in contamination in both places. Several thousand people who worked at these sites were screened for spore exposure by collecting nasal swab samples. We describe here a screening protocol which we, as a level A laboratory, used on very short notice to process a large number of specimens (3,936 swabs) in order to report preliminary results as quickly as possible. Six isolates from our screening met preliminary criteria for Bacillus anthracis identification and were referred for definitive testing. Although none of the isolates was later confirmed to be B. anthracis, we studied these isolates further to define their biochemical characteristics and 16S rRNA sequences. Four of the six isolates were identified as Bacillus megaterium, one was identified as Bacillus cereus, and one was an unidentifiable Bacillus sp. Our results suggest that large-scale nasal-swab screening for potential exposure to anthrax spores, particularly if not done immediately postexposure, may not be very effective for detecting B. anthracis but may detect a number of Bacillus spp. that are phenotypically very similar to B. anthracis.     

Molecular Cytogenetic Analysis of Tetraploid and Hexaploid Aegilops Crassa

The distribution of highly repetitive DNA sequences on chromosomes of tetraploid and hexaploid cytotypes of Aegilops crassa (Dcr1Xcr and Dcr1XcrDcr2 genomes) was studied using C-banding and in situ hybridization analyses with the pSc119, pAs1 and pTa794 DNA clones. In total, 14 tetraploid and five hexaploid accessions were examined. All chromosomes can be identified by their C-banding and ISH pattern with the pAs1 DNA clone. Only a few pSc119 hybridization sites were observed in the telomeric regions of several chromosomes. We found a high level of C-banding polymorphism and only minor variations in labeling patterns. The position of C-bands generally coincided with the location of the pAs1 sequence. Three 5S rDNA loci were detected in tetraploid Ae. crassa, whereas five pTa794 ISH sites were observed in 6x Ae. crassa. All the hexaploid accessions differed from the tetraploids by a reciprocal non-centromeric translocation involving chromosomes A and N. Three additional translocations were detected in the accessions analyzed. The Dcr1 genome of 4x Ae. crassa is highly modified compared with the D genome of the progenitor species Ae. tauschii. Because of the large amount of chromosomal rearrangements, the origin of the Xcr genome remains unknown. The second Dcr2 genome of 6x Ae. crassa is different from the Dcr1 genome but is similar to the D-genome chromosomes of Ae. tauschii, indicating that no additional large rearrangements occurred at the hexaploid level.     

Purification and characterization of placental heparanase and its expression by cultured cytotrophoblasts

The role of different extracellular matrix (ECM)-degrading enzymesin the normal functioning of the placenta is well documented.Heparan sulphate proteoglycan (HSPG) is an integral constituentof the placental and decidual ECM. Because this proteoglycanspecifically interacts with various macromolecules in the ECM,its degradation may disassemble the matrix. Hence, in the caseof the placenta, this may facilitate normal placentation andtrophoblast invasion. Crude placental specimens were collectedfrom first and third trimester placentas. Heparanase (endo-P-glucuronidase)was isolated and purified by ammonium sulphate precipitationfollowed by sequential chromatographies on carboxymethyl-, heparin-and ConA-Sepharose columns. The placental enzyme was furthercharacterized for its molecular weight and specific inhibitionby heparin, and was shown to resemble heparanase expressed byhighly metastatic tumour cells and activated cells of the immunesystem. In order to locate the source of heparanase activityin the placenta, primary cytotrophoblast cultures were established.Intact cells, as well as conditioned medium and cell lysates,were analysed for heparanase activity using metabolically sulphate-labelledECM as a natural substrate. Heparanase was highly active inlysates of cytotrophoblasts. This activity was also expressedby intact cytotrophoblasts seeded on ECM, but no activity couldbe detected in the culture medium. Incubation of the cytotrophoblastsin contact with ECM resulted in release of ECM-bound basic fibroblastgrowth factor (bFGF). We propose that the cytotrophoblasticheparanase facilitates placentation, through cytotrophoblastextravasation and localized neovascularization. cytotrophoblast/extracellular matrix/heparanase/heparan sulphate proteoglycan/placenta     

In vivo inhibition by a monoclonal antibody to CD4+ T cells of humoral and cellular immunity in sheep.

The ability of intravenously injected anti-CD4 and anti-CD8 monoclonal antibody (mAb) to deplete specific lymphocyte subsets in vivo and their effects on antibody responses to ovalbumin (OVA) and Brucella abortus, and skin reactivity to T-cell mitogens was examined in merino lambs. Repeated administration of anti-CD4 or anti-CD8 mAb caused a specific and sustained depletion of target cells from peripheral blood. Anti-CD4 mAb significantly inhibited the in vivo antibody response to OVA but had no effect on the antibody response to LPS of B. abortus. In contrast, antibody responses to both OVA and B. abortus lipopolysaccharides (LPS) remained unaffected in lambs depleted of their CD8+ T lymphocytes. These results confirm the T-cell dependence and independence of antibody responses to OVA and LPS, respectively. Skin reactions elicited by intradermal injections of phytohaemagglutinin (PHA) and concanavalin A (Con A) were also significantly suppressed in lambs depleted of their CD4+ T cells, but treatment with anti-CD8 mAb had no effect on skin responsiveness. Together, these results suggest that mAb can be extremely effective at selectively depleting lymphocyte subsets in vivo and can be used for studying various aspects of immunoregulation and immunity in sheep.     

Leucocytozoonosis in the Israeli sparrow, Passer domesticus biblicus Hartert 1904

Among the 91 house sparrows (Passer domesticus biblicus Hartert, 1904) examined and caught in the Jordan valley, Israel, 79% were found to be infected with Leucocytozoon fringillinarum Woodcock 1910. In the coastal plain of Israel (South of Tel Aviv), Leucocytozoon infection was found in only 3 out of 43 examined sparrows. In the birds examined, Leucocytozoon gametocytes were present, often in large numbers, in the circulating blood of the visceral organs, whereas they were only sporadic or even absent in the peripheral blood. Gametocytes were seen in the brain capillaries in only a few birds. Only one of the heavily infected sparrows was anemic. Leucocytozoon merozoites were present in the liver and kidneys in only a few infected birds. Merogonic infections did not induce any severe pathological changes, while the gametocyte congestion caused dilation of the blood vessels and sinuses. Tissue damage by the gametocyte parasitemia was most evident in the liver and kidneys. Leucocyte infiltration developed alongside the affected vessels; diffuse necrosis developed in the infiltrated areas. In the kidneys, many tubules were degenerated. Leucocytozoon gametocyte infection in sparrows is unique in that it appears to be confined, for most of its duration, to the visceral circulation, resulting in clinical consequences. Geographically, it is confined to habitats presumably supporting vectors.     

The methionine allele of the COMT polymorphism impairs prefrontal cognition in children and adolescents with ADHD

ADHD is a highly heritable psychiatric disorder of childhood. A functional polymorphism (Val158Met) of the catechol-O-methyltransferase (COMT) gene has attracted interest as a candidate gene for ADHD. The high-activity valine variant of this polymorphism degrades prefrontal dopamine three to four times more quickly than the low-activity methionine variant and could therefore contribute to the proposed hypodopaminergic state in ADHD. Here we tested for association of this polymorphism with ADHD and examined its influence on prefrontal cognition in ADHD. We have previously reported no association of the Val158Met COMT gene polymorphism in 94 Irish ADHD families (Hawi et al. (2000) Am J Med Genet 96:282–284). Here we re-examined this finding with an extended sample of 179 ADHD cases using a family control design. We also examined the performance of children and adolescents with ADHD (n=61) on a standardised test of sustained attention. Analysis confirmed the absence of an association between the Val158Met COMT gene polymorphism and the clinical phenotype of ADHD. COMT genotype, however, affected prefrontal cognition in ADHD: ADHD children who were homozygous for the valine variant had significantly better sustained attention than those ADHD children possessing at least one copy of the methionine variant. Children possessing the methionine variant performed significantly below age-related norms on tests of sustained attention. Contrary to expectations, the methionine variant of the Val158Met COMT gene polymorphism impaired prefrontally-mediated cognition in ADHD. This effect may be understood by positing a hyper-functioning of prefrontal dopaminergic systems. Against this background, the slower clearance of dopamine associated with the methionine variant of the COMT gene polymorphism may be disadvantageous to cognition in ADHD.Mark Bellgrove and Katharina Domschke contributed equally to this work and should therefore both be considered first authors. The work reported herein was supported by a grant from the Irish Health Research Board.     

Renal transplantation in pre-school children

This short report describes the outcome of 13 renal transplants in 11 children under 5 years of age. Nine (82%) of the 11 recipients are alive; 2 children died with functioning grafts. Approximately 50% of grafts are functioning at 5 years post transplantation. Children with congenital kidney malformations can be successfully managed to transplantation.