Donor resting B cells induce indefinite prolongation of fully allogeneic cardiac grafts when delivered with anti-immunoglobulin-D monoclonal antibody: evidence for tolerogenicity of donor resting B cells in vivo

BACKGROUND: Resting B (rB) cells have been shown to induce T-cell anergy in vitro and to prolong the survival of skin and cardiac grafts mismatched for minor histocompatibility antigens. However, rB cells were unable to modulate the rejection response when grafts mismatched for major histocompatibility complex antigens were transplanted. We reasoned that donor antigens, which presented via the indirect pathway by recipient antigen-presenting cells, in particular B cells, might influence the ability of rB cells to induce unresponsiveness. To explore this hypothesis, we used an anti-immunoglobulin (Ig)-D monoclonal antibody (mAb) specific for recipient B cells to deplete these cells, thereby decreasing the potential for indirect presentation in vivo. METHODS: CBA mice were pretreated with 1 x 10(7) donor rB or activated B (aB) cells 7 days before transplantation of a C57BL/10 cardiac graft in the absence or presence of anti-IgD mAb. RESULTS: Naive CBA mice rejected C57BL/10 grafts acutely (median survival time [MST]=8 days). Pretreatment with rB cells alone resulted in a modest prolongation of graft survival (MST=11.5 days). In marked contrast, when rB cells were delivered with anti-IgD mAb, indefinite graft prolongation (MST>100 days) was observed in all recipients. Interestingly, aB cells produced only a small prolongation of graft survival when delivered with anti-IgD mAb (MST=15 days). Recipients treated with anti-IgD mAb alone rejected C57BL/10 cardiac allografts acutely (MST=8 days). CONCLUSION: These data suggest that depletion of recipient B cells in vivo can augment the ability of donor rB cells to induce indefinite prolongation of fully allogeneic cardiac grafts. Thus, IgD+ B cells in the recipient may influence the development of unresponsiveness in vivo.     

Relationship between soluble CD14, lipopolysaccharide binding protein, and the alveolar inflammatory response in patients with acute respiratory distress syndrome

The effects of bacterial endotoxin (lipopolysaccharide, LPS) are amplified by lipopolysaccharide binding protein (LBP) and CD14, resulting in cellular activation at very low concentrations of LPS. To investigate the importance of this pathway in acute lung injury, we measured LPS, LBP, and soluble CD14 (sCD14) in the bronchoalveolar lavage fluid (BAL) of 82 patients with acute respiratory distress syndrome (ARDS). LBP and sCD14 increased markedly in BAL of patients with ARDS. sCD14 and LBP each were strongly related to BAL total protein and polymorphonuclear neutrophil (PMN) concentration, whereas LPS concentration was not. Multivariate analyses showed sCD14 to be strongly related to BAL total protein, even after controlling for LPS and LBP concentrations. sCD14 was strongly and independently related to PMN concentration, after controlling for BAL LPS, LBP, and interleukin-8 (IL-8). The BAL LPS concentration was not strongly related to either BAL total protein or BAL PMN. The BAL sCD14 and LBP values were similar in all subgroups of patients with ARDS, and were not related to survival. The serum LBP and sCD14 were elevated in ARDS, but were not related to BAL total protein, LBP, sCD14, PMN, or clinical outcome. Thus, LBP and sCD14 reach high concentrations in the lungs of patients with ARDS, and BAL sCD14 is strongly related to two major indices of lung inflammation: total protein and PMN concentration. CD14-dependent mechanisms may contribute to lung inflammation in ARDS.     

Regulation of peripheral vascular tone in patients with heart failure: contribution of angiotensin II

This study evaluated the effects of stimulus repetition rate, phase, and frequency on the auditory brainstem response (ABR) in normal-hearing neonates and adults. In both neonates and adults, the results clearly showed large ABR wave V latency differences between condensation and rarefaction for low-frequency stimuli. Phase dependent latency effects are believed to be a result of the phase-sensitive low-frequency neurons. Increasing stimulus repetition rate produced greater wave V latency shift in neonates than in adults. The consequences of rate changes were independent of stimulus phase and frequency.     

Clinical implications of genetic polymorphisms and drug interactions mediated by cytochrome P-450 enzymes

Hepatic oxidation is a major drug metabolising process and is carried out by the cytochrome P-450 monooxygenase system. This system consists of a variety of isoenzymes among which the cytochromes 1A2, 2C8, 2C9/10, 2C19, 2D6, 2E1 and 3A4 are involved in the oxidative metabolism of drugs. Interindividually, large differences in capacities are found. These differences are partly due to genetic constitution (genetic polymorphism, which has been proved to exist for CYP2D6 and CYP2C19) and partly due to environmental factors, among which the administration of interfering drugs can play a major role.     

Zinc transport across an endothelium includes vesicular cotransport with albumin

Bovine pulmonary arterial endothelial cells (BPAEC) were grown on permeable polycarbonate membrane filters suspended between two compartments representing the blood vessel lumen and the interstitium. This in vitro model of an endothelium was subjected to a battery of tests to unravel the mechanisms of zinc transport from the blood into peripheral tissues. Transport of 65Zn across BPAEC from media containing zinc concentrations up to 50 mumol/L exhibited both saturable and nonsaturable kinetics. Vmax of the saturable component was 246 +/- 43 pmol/(h x cm2) and Km was 2.3 +/- 1.3 mumol/L. Transport was pH and temperature sensitive and substantially influenced by albumin and histidine concentrations, but not influenced by analogous minerals or metabolic inhibitors. Inhibition of coated vesicle formation by depletion of intracellular potassium reduced 65Zn transport. Albumin carrying a zinc ion crossed the endothelium more rapidly than zinc-free albumin. When evaluated together, this body of evidence supports the existence of two major pathways of zinc transport across the pulmonary endothelium, but neither involves entry into the endothelial cells. One pathway involves receptor-mediated cotransport with albumin by transcytotic vesicles. The other is nonsaturable and involves cotransport with albumin and low molecular weight ligands, principally histidine, through intercellular junctions and nonselective, bulk-fluid transcytosis.     

Genetic approaches to the function of insulin-like growth factor-binding proteins during rodent development

Gene targeting provides a direct method for introducing mutations into specific mouse loci. This approach has been used productively to demonstrate that insulin-like growth factor (IGF) peptides and receptors are required for normal prenatal growth. Six genes comprising a third major component of the IGF system, the IGF-binding proteins (IGFBPs), are all expressed during prenatal rodent development. One of these genes, IGFBP-2, has also been disrupted using gene targeting, and homozygous null BP-2 mice are characterized by a decreased spleen size and an increase in circulating levels of other IGFBPs. These alterations are less dramatic than initially expected based on the fetal IGFBP-2 expression pattern. These results are discussed in light of both other genetic ablations involving members of gene families and in the context of the expression of other IGFBPs in rodent fetal and uterine tissues.     

Selective amplification via biotin- and restriction-mediated enrichment (SABRE), a novel selective amplification procedure for detection of differentially expressed mRNAs

We present a novel subtractive enrichment protocol for the identification of differentially expressed mRNA species. This procedure, called SABRE (selective amplification via biotin- and restriction-mediated enrichment), uses selective streptavidin-biotin affinity and restriction enzyme site reconstitution to enrich for cDNA species more abundant in one population than in another. Analysis of liver cDNA from a mouse strain expressing the neomycin resistance gene demonstrated that this procedure is capable of identifying species present in one population but absent from another. Furthermore, experiments to identify genes with circadian expression patterns in mouse liver demonstrated that SABRE is capable of detecting even modest 2- to 10-fold differences in accumulation of moderately rare mRNA species, representing as little as 0.03% of total mRNA. These experiments identified the gene encoding coumarin 7-hydroxylase as displaying circadian expression in mouse liver.