Role of T cell costimulation in anti-viral immunity

Members of both the CD28 and TNFR families can have costimulatory roles in T cell activation. Gene targeted mice as well as in vivo blocking experiments have established distinct roles for CD28/B7; ICOS/ICOSL; CD27/CD70; 4-1BB/4-1BBL and OX40/OX40L during viral infection. Many issues remain to be addressed, including the timing and location of the interactions, the possibility of partial redundancy between related family members and the molecular basis for the specific phenotypes observed in the different gene targeted mice.     

Spatial distribution of DNA-synthesizing cells in colonic crypts of the guinea pig

The ascending colon of a guinea pig injected with tritiated thymidine was cut serially, autoradiographed and stained with periodic-acid-Schiff-hematoxylin. Maps of transversely sectioned crypts were prepared with the use of a microscope eye-piece projector. The number and angular positions of pulselabelled (DNA-synthesizing) cells around the circumference of transverse sections of the crypt were recorded. A method of “statistics of the circumference” was applied in order to find the variances of angular distances between labelled cells and thereby to find the type of arrangement of DNA-synthesizinbg cells in the crypt. The spatial distribution of DNA-synthesizing cells, both around the crypt circumference and along the crypt, was found to be non-random. While the pattern of nonrandomness around the crypt circumference is such that the DNA-synthesizing cells tend to occupy positions in the crypt circumference at maximal distances from each other, DNA-synthesizing cells along the crypt tend to occupy positions at minimal distances from each other. DNA-synthesizing cells are arranged in the crypt in rows, each consisting of several cells and each parallel to the long axis of the crypt. Apparently the dividing cell of the crypt produces either two proliferating or two differentiating cells. No evidence of differential mitosis could be found.     

Guinea-pig peritoneal macrophage receptor for IgG--II. Purification of the receptor and its partial characterization

The Fc gamma receptor of guinea-pig peritoneal macrophages was purified by affinity chromatography by using rabbit IgG or guinea-pig IgG2 coupled to Sepharose. Lysates prepared by treatment of 125I-labeled macrophages with NP-40 were first applied to BSA-Sepharose and then to IgG-Sepharose and eluted with 0.5 M acetic acid containing 1% NP-40. The specific binding was determined by interaction of the 125I-labeled receptor with IgG-Sepharose in the presence and absence of soluble IgG. The specific binding of the purified receptor was 42-82%. Interactions of the purified receptor with IgG-Sepharose were equally well inhibited by soluble rabbit IgG or guinea-pig IgG2, but not by F(ab')2 fragments. Inclusion of NP-40 in the buffer used in the assay reduced nonspecific binding of the receptor to the affinity gels. The purified receptor can be stored for 20 days at 4 degrees C without a significant loss of the specific binding activity. Analysis of the receptor by SDS-polyacrylamide gel electrophoresis, under nonreducing and reducing conditions, revealed two major peaks of radioactivity corresponding to mol. wts of about 50,000 and 25,000, and one very minor peak corresponding to a mol. wt of about 30,000. The results obtained suggest that the protein of the second major peak is a product of the dissociation of the protein of the first major peak rather than a product of its reduction by 2-mercaptoethanol.     

Central tolerance: Clonal deletion or clonal arrest?

Studies in various experimental animals have shown that developing T cells with specificity for self antigens can be prevented from maturation at an early stage of development. While several in vitro and in vivo experiments have shown that the mechanism of silencing autospecific T cells is the deletion of immature CD4⁺8⁺ thymocytes other experiments were interpreted to indicate that tolerance could also result from developmental arrest of more immature CD4^?8⁺ thymocytes not involving cell death. Here we show that immature CD4^?8⁺ cells when confronted with T cell receptor ligands in vitro neither survive nor differentiate into cells which cannot be deleted, indicating that clonal elimination rather than developmental arrest is the mechanism of central tolerance of all immature T cells.     

Expression and function of 4-1BB during CD4 versus CD8 T cell responses in vivo

4-1BBL(-/-) mice have a defect in recall CD8+ T cell responses to viruses, whereas CD4+ T cell responses to virus are unimpaired in these mice. In contrast, both CD4+ and CD8+ T cells respond to 4-1BB ligand (4-1BBL) in vitro. To clarify the role of 4-1BB/4-1BBL in CD4+ versus CD8+ T cell responses in vivo, we compared CD4 (OT-II) and CD8 (OT-I) TCR transgenic T cells responding to the same antigen in an in vivo adoptive transfer model in 4-1BBL(+/+) versus 4-1BBL(-/-) mice. During primary and secondary responses, expression of 4-1BB on in vivo-activated TCR transgenic T cells was earlier and more transient than previously observed in vitro, correlating with expression of the early activation antigen CD69 and preceding the transition to the CD44hi state. Although 4-1BB is expressed early in the primary response, there was no effect of 4-1BBL deficiency on initial CD8 T cell expansion and only a minor effect on initial CD4 T cell expansion. The major effect of 4-1BB/4-1BBL interaction is on the T cell recall response. This is due to effects of 4-1BBL on maintenance of T cell numbers at the end of the primary response with additional effects of 4-1BBL on secondary expansion of T cells.     

I-J as an Inducible T Cell Receptor for Self

"Jedenfalls, wenn man davorsteht, dann sieht man sich selbstaber eben nicht wie in einem gewöhnlichen Spiegel, versteht sich. Man sieht nicht sein Äusseres, sondern man sieht sein wahres inneres Wesen. so wie es in Wirklichkeit beschaffen ist. Wer da durch will, der muß - um es mal so auszudrücken -in sich selbst hineingehen."
Die undendliche Geschichte, bei Michael Ende, K. Thiehemanns Verlag, Stuttgart, 1979.     

The cGMP synthesis and PKG1 expression in murine lymphoid organs

Numerous reports indicate that cyclic 3',5' guanosine monophosphate (cGMP) is involved in the regulation of immune processes. However, the mechanisms responsible for the synthesis of this nucleotide and its signaling pathways in immune cells are still not well recognized. The aim of our studies was to establish: 1) which form of guanylyl cyclase (GC) synthesizes cGMP in murine lymphoid organs and 2) whether the same organs express the isoforms PKG1alpha and/or PKG1beta of protein kinase G, known as possible target for synthesized cGMP. Cells isolated from thymus, lymph nodes, and spleen were treated with activators (SNP, ANP, CNP, STa) of soluble or particulate cyclases. Sodium nitroprusside (SNP) elevated intracellular cGMP 2-fold in thymic and lymph node cells and about 10-fold in spleen cells. Atrial natriuretic peptide (ANP) caused modest but statistically significant increases of cGMP in cells of all three organs. Additionally, spleen cells elevated their cGMP content about 2-fold in response to C-type natriuretic protein (CNP). In cellular homogenates of the all analyzed organs, the antibody anti-PKG1beta stained the 78 kDa band corresponding to the molecular mass of PKG1. Only homogenates of spleen cells were stained by the antibody recognizing PKG1alpha. Our results indicate that in the investigated organs cGMP may be synthesized mainly by soluble GC in response to nitric oxide. The modest increase of cGMP upon stimulation by ANP suggests that in all these organs either exists only a small subpopulation of cells that express particulate cyclase GC-A or GC-A is expressed at very low level. In spleen cells, however, cyclase GC-B appears to be the more active enzyme. Elevated cGMP concentration may in turn activate PKG1beta in thymus, lymph node, and spleen cells and also PKG1alpha in spleen cells.     

Histamine Intolerance in Children: A Narrative Review

Histamine intolerance is defined as a disequilibrium of accumulated histamine and the capacity for histamine degradation. This clinical term addresses a non-immunologically mediated pathology when histamine ingested with food is not particularly high, however its degradation is decreased. This paper aims to provide a narrative review on etiopathology, epidemiology, possible diagnostic algorithms and diagnostic challenges of histamine intolerance in children. The clinical picture of histamine intolerance in children is similar to that observed in adults apart from male predominance found in paediatric patients. Both in children and adults, a histamine-reduced diet is typically the treatment of choice. Diamine oxidase supplementation offers another treatment option. There is no symptom or test pathognomonic for histamine intolerance. Nevertheless, manifestations of chronic gastrointestinal symptoms, measurements of diamine oxidase deficits, positive results of histamine provocation tests and improvement in symptoms with histamine-reduced diet considerably increase the probability of histamine intolerance diagnosis. These factors have been included in the proposed diagnostic algorithm for histamine intolerance. In children histamine intolerance most likely co-occurs with allergies and bowel diseases, which creates an additional diagnostic challenge. As the evidence for children is poor further research is needed the determine epidemiology, validate diagnostic algorithms and establish possible treatment options regarding histamine intolerance.     

Botanicals in Postmenopausal Osteoporosis

Osteoporosis is a systemic bone disease characterized by reduced bone mass and the deterioration of bone microarchitecture leading to bone fragility and an increased risk of fractures. Conventional anti-osteoporotic pharmaceutics are effective in the treatment and prophylaxis of osteoporosis, however they are associated with various side effects that push many women into seeking botanicals as an alternative therapy. Traditional folk medicine is a rich source of bioactive compounds waiting for discovery and investigation that might be used in those patients, and therefore botanicals have recently received increasing attention. The aim of this review of literature is to present the comprehensive information about plant-derived compounds that might be used to maintain bone health in perimenopausal and postmenopausal females.