FM sonography in diffuse liver disease: prospective assessment and blinded analysis

FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease.     

CD40 expression by gingival fibroblasts: correlation of phenotype with function

CD40, a member of the tumor necrosis factor-alpha receptor family, is constitutively expressed by cells of hematopoietic and non- hematopoietic origin, including fibroblasts. Signaling through this receptor molecule regulates inflammatory cytokine secretion by many cell types. Based on the recently described cytokine secretory heterogeneity of fibroblast cell subsets, we hypothesized that secretion of inflammatory cytokines by gingival fibroblast cultures may be dictated by the existence of differential proportions of cytokine- secreting subpopulations which express high levels of CD40. After examining a large number of gingival fibroblast (GF) cultures we find that the frequency of IL-6- and IL-8-secreting cells mirrors the frequency of cells expressing high levels of CD40 in these cultures. In addition, we demonstrate a direct functional relationship between CD40 expression and IL-6 or IL-8 secretion by showing that ligation of this molecule on GF, and CD40+ fibroblast subsets in particular, up- regulates secretion of these cytokines in vitro.      

Regulation of autoreactive anti-IgG (Rheumatoid Factor) B cells in normal and autoimmune mice

In systemic autoimmune disease, autoantibodies target specific self-components in patterns that depend on the particular underlying disease. Therefore, in order to understand how tolerance to these self-components breaks down, it is important to study B cells with those specificities, rather than artificial autoantigens. We have been investigating the regulation of autoreactive B cells with specificity for self IgG2a (the rheumatoid factor or RF specificity) in order to understand how normal mice regulate RF autoantibodies and how this fails in autoimmune mice. A transgenic (Tgic) mouse based on an RF isolated from a diseased MRL/lpr/lpr mouse was constructed and studied in both normal and autoimmune-prone genetic backgrounds. Normal mice do not appear to regulate the RF clone negatively, nor do they appear to activate it substantially. Thus, a disease-related RF is "clonally indifferent." However, in a, Fas-deficient autoimmune-prone animal, these RF B cells are activated to divide and secrete in an antigen-specific manner. A high-affinity RF Tgic mouse was also constructed to determine whether RFs could be tolerized in normal mice. These B cells were deleted or edited in the presence of the autoantigen, which originated from maternal IgG in young mice. Interestingly, shortly after weaning, many mice began to produce autoreactive RF. Escape from tolerance could last for months and was most likely perpetuated by a positive feedback mechanism. Such a mechanism could exist in autoimmune animals and could have important implications for chronic autoimmune disease, as discussed.     

Identification of MEN1 gene mutations in sporadic carcinoid tumors of the lung

Lung carcinoids occur sporadically and rarely in association with multiple endocrine neoplasia type 1 (MEN1). There are no well defined genetic abnormalities known to occur in these tumors. We studied 11 sporadic lung carcinoids for loss of heterozygosity (LOH) at the locus of the MEN1 gene on chromosome 11q13, and for mutations of the MEN1 gene using dideoxy fingerprinting. Additionally, a lung carcinoid from a MEN1 patient was studied. In four of 11 (36%) sporadic tumors, both copies of the MEN1 gene were inactivated. All four tumors showed the presence of a MEN1 gene mutation and loss of the other allele. Observed mutations included a 1 bp insertion, a 1 bp deletion, a 13 bp deletion and a single nucleotide substitution affecting a donor splice site. Each mutation predicts truncation or potentially complete loss of menin. The remaining seven tumors showed neither the presence of a MEN1 gene mutation nor 11q13 LOH. The tumor from the MEN1 patient showed LOH at chromosome 11q13 and a complex germline MEN1 gene mutation. The data implicate the MEN1 gene in the pathogenesis of sporadic lung carcinoids, representing the first defined genetic alteration in these tumors.      

High-dose chemotherapy followed by reinfusion of selected CD34+ peripheral blood cells in patients with poor-prognosis breast cancer: a randomized multicentre study.

Seventy-one patients with poor-prognosis breast cancer were enrolled after informed consent in a multicentre randomized study to evaluate the use of selected peripheral blood CD34+ cells to support haematopoietic recovery following high-dose chemotherapy. Patients who responded to conventional chemotherapy were mobilized with chemotherapy (mainly high-dose cyclophosphamide) and/or recombinant human granulocyte colony-stimulating factor (rhG-CSF). Patients who reached the threshold of 20 CD34+ cells per microl of peripheral blood underwent apheresis and were randomized at that time to receive either unmanipulated mobilized blood cells or selected CD34+ cells. For patients in the study arm, CD34+ cells were selected from aphereses using the Isolex300 device. Fifteen patients failed to mobilize peripheral blood progenitors and nine other patients were excluded for various reasons. Forty-seven eligible patients were randomized into two comparable groups. CD34+ cells were selected from aphereses in the study group. Haematopoietic recovery occurred at similar times in both groups. No side-effect related to the infusion of selected cells was observed. The frequency of epithelial tumour cells in aphereses was low (8 out of 42 evaluated patients), as determined by immunocytochemistry. We conclude that selected CD34+ cells safely support haematopoietic recovery following high-dose chemotherapy in patients with poor-prognosis breast cancer.     

Distinct roles for donor- and host-derived antigen-presenting cells and costimulatory molecules in murine chronic graft-versus-host disease: requirements depend on target organ

The application of allogeneic stem cell transplantation (alloSCT) is limited by graft-versus-host disease (GVHD). GVHD can be divided into acute and chronic forms that likely have different requirements for initiation and pathogenesis mechanisms. In prior studies we demonstrated that residual host antigen-presenting cells (APCs) were required to initiate acute GVHD (aGVHD) mediated by CD8 T cells. In contrast, here we demonstrate that either donor or host APCs can initiate CD4-mediated GVHD in a model that has features of chronic GVHD (cGVHD). Both donor and host APCs must provide CD80/86-dependent costimulation to elicit maximal cGVHD, and there is no GVHD when both donor and host lack CD80/86. Finally, we were surprised to find that, although either donor or host APCs are sufficient to stimulate skin cGVHD, donor APCs play a dominant role in intestinal cGVHD. Both CD40 and CD80/86 are critical for donor APC function in intestinal cGVHD, but only CD80/86 is required for skin cGVHD. Thus, there are target-tissue-specific differences in APC requirements. These results identify differences in APC requirements between CD8-mediated aGVHD and CD4-mediated cGVHD. They further highlight donor APCs as additional targets for GVHD therapy.     

Antigen presentation and transfer between B cells and macrophages

B cells play an active role in directing immunity against specific proteins in part because of their capacity to sequester antigen via B cell receptor (BCR). Our prior findings indicate that B cells can initiate an immune response in vivo to self proteins independent of other antigen-presenting cells (APC). However, these studies also demonstrated that both dendritic cells and macrophages are important in the ongoing immune response. The present work illustrates a mechanism by which antigen acquired by B cells through BCR is specifically transferred to other APC, in particular, macrophages. The transfer of antigen is dependent on the specificity of BCR and requires direct contact between the cells, but does not require MHC compatibility between the cells and is independent of the activation state of macrophages. Antigen transfer is functional, in that macrophages, which received B cell derived-antigen, can activate CD4 T cells. Overall, these results define a novel mechanism by which B cells can focus immunity toward a specific antigen and transfer the ability to activate CD4 T cells to other APC.