In vivo expression of the B7 costimulatory molecule by subsets of antigen-presenting cells and the malignant cells of Hodgkin's disease

The B-lymphocyte/accessory-cell activation antigen B7 (BB1) has been shown in vitro to stimulate T-lymphocyte proliferation and cytokine production via CD28 present on the latter cells. In this study, benign lymphoid tissues, lymphomas, and extralymphoid inflammatory sites were examined immunohistochemically using anti-B7 and other relevant monoclonal antibodies. B7 was expressed by benign transformed germinal center B cells, as it was by B cells of follicular lymphomas. B7 was also expressed by a subpopulation (a mean of 31% to 65%) of macrophages and dendritic cells in a variety of lymphoid tissues. It was present in abundance on all macrophages constituting sarcoid granulomas in lymph nodes. In extralymphoid inflammation, 17% to 35% of macrophages expressed B7 only weakly. Cases of Hodgkin's disease showed expression of B7 by the majority of Reed-Sternberg cells or malignant mononuclear variants, a phenomenon that potentially contributes to the lymphocytic accumulation that is a feature of this condition. CD28+ T cells were seen in all areas where T cells were present. B7+ and CD28+ cells colocalized in, for example, lymphoid follicles, lymph node paracortex, sarcoid granulomas, and Hodgkin's disease tissue, indicating a potential for cellular interaction via these molecules at these sites.     

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.     

Regulation of stimulated integrin surface expression in human neutrophils by tyrosine phosphorylation

The control of the adhesive properties of human neutrophils is an essential element of their defense function. One level at which this control is exerted involves the upregulation of the surface expression of beta 2-integrins. In this study, we have examined the potential involvement of tyrosine phosphorylation in the latter process. Two inhibitors of tyrosine kinases with differing modes of action, erbstatin and herbimycin A, were found to inhibit the expression of CD11b and CD18 stimulated by chemotactic factors (fMet-Leu-Phe or leukotriene B4) or growth factors (tumor necrosis factor alpha). This inhibition was not shared by an inactive analog of erbstatin or by the protein kinase C inhibitor Ro 31-8330. Erbstatin also inhibited the unveiling of activation-specific neoepitopes detected by antibody CBRM1/5. Pretreatment of neutrophils (but not of endothelial cells) with erbstatin inhibited the stimulation of neutrophils' adherence to endothelial cells induced by fMet-Leu-Phe. Augmentation of tyrosine phosphorylation by inhibiting tyrosine phosphatases using hydroperoxyvanadate led to an increased surface expression of CD11b and CD18 and enhanced the adhesion of neutrophils to endothelial cells. Finally, the leumedin NPC 15669, which had previously been shown to inhibit stimulated CD11b expression and neutrophil adherence to endothelial cells and to exhibit anti-inflammatory properties in various in vivo models of inflammation, inhibited the stimulation of tyrosine, phosphorylation induced by fMet-Leu-Phe. Taken together, these data establish a strong correlation between tyrosine phosphorylation and integrin upregulation in stimulated human neutrophils.     

Assessing the delivery of neutrophils to tissues in neutropenia

Studies of neutrophil kinetics in neutropenic individuals, as well as clinical observations of variability in the occurrence of infection among patients with neutropenia, have suggested that blood neutrophil counts may not uniformly reflect the effective delivery of neutrophils to extravascular tissues where the cells perform their principal host defense functions. To evaluate this possibility we developed a sensitive, reproducible method of measuring the extravascular delivery of neutrophils to a normal mucosal site of neutrophil turnover. This method is based upon the quantification of neutrophils recoverable from saline mouth wash specimens. Twenty-five mL specimens, obtained in a controlled manner from neutropenic patients and normal subjects, were centrifuged and the sediments resuspended in 1.0 mL Hank's buffer with 2 micrograms acridine orange, incubated at 37 degrees C for 15 minutes, and then examined in a hemocytometer chamber by fluorescence microscopy. Neutrophils could be clearly distinguished by their characteristic fluorescence and were counted. With this method as few as 1,500 neutrophils were detected reliably in mouth wash specimens. Mucosal neutrophil counts varied less than 10% with repeated sampling of individual subjects over 5-day periods and were consistently greater than 1.3 X 10(5)/specimen in non-neutropenic individuals. Although profound neutropenia was generally reflected by lower than normal oral mucosal neutrophil counts, these counts were significantly higher in individuals with chronic severe neutropenia (blood neutrophils less than 300/mm3) than in patients with acute neutropenia of comparable severity that had developed following chemotherapy. Also, in individuals recovering from profound neutropenia, neutrophils usually reappeared earlier in mouth wash specimens than in blood, and oral mucosal neutrophil counts attained recovery levels more rapidly than did blood counts. This phenomenon was particularly evident in an individual with cyclic neutropenia. Moreover, mucosal neutrophils could occasionally be detected in profoundly neutropenic patients when neutrophils were not present in blood samples. These findings indicate that mucosal neutrophil counts in individuals with neutropenia provide information about the delivery of neutrophils to tissues that may not be apparent from blood neutrophil counts alone.     

Is antibiotic prophylaxis to prevent infective endocarditis worthwhile?

Infective endocarditis (IE) is a rare condition which is associated with considerable morbidity and mortality. Almost 100 years ago, the links between endocarditis and procedures, particularly dental procedures, were postulated. Over 50 years ago the first guidelines recommending antibiotic prophylaxis (AP), with the aim of preventing IE developing after procedures, were proposed. However, there has only ever been circumstantial evidence in humans that AP prevents IE. The rarity of IE has made a randomised controlled clinical trial impractical to date. This article outlines the history of AP and reviews the evidence base for the use of AP to prevent IE.     

Response to hormones of cells cultured from human giant cell tumors of bone.

Giant cell tumors of bone obtained from 7 patients were dispersed with clostridial collagenase and trypsin and adherent cells were maintained in culture. Early cultures contained both mononucleated and multinucleated cells presumably derived from the stromal and giant cells of the original tumor. The original multinucleated cells did not survive for greater than 7-10 days whereas the mononucleated cells persisted and could be passaged by trypsinization. In 5 of 7 early cultures exposed to parathyroid hormone (PTH) there was a rise in cAMP within 5-10 min in both cells and medium which averaged approximately 12-fold. None of the cells responded to calcitonin and a variable rise in cAMP was seen after incubation with prostaglandin E2. In cells cultured from 3 tumors the PTH response disappeared with passage of the cells, but in the remaining 2, PTH response persisted through multiple passages. The presence as well as the magnitude of the PTH-induced cAMP response in these cells is consistent with a skeletal origin.     

Human recombinant interleukin-1 beta and -alpha, but not recombinant tumor necrosis factor alpha stimulate ACTH release from rat anterior pituitary cells in vitro in a prostaglandin E2 and cAMP independent manner

The pituitary-adrenal axis is known to be stimulated during the acute-phase response. As cytokines play a central role in mediating the constellation of host response occurring during the acute-phase response it was of interest to assess the ability of cytokines to stimulate ACTH secretion from normal pituitary cells in culture. We used human recombinant interleukin-1 beta and -alpha (hrIL1 beta, hrIL1 alpha) and human recombinant tumor necrosis factor alpha (hrTNF alpha) to analyze the ability of these cytokines to induce ACTH secretion from normal rat anterior pituitary cells in culture. We also investigated the possible roles of prostaglandin E2 (PGE2) and cAMP in the cellular transduction mechanism. After 3 days of incubation primary cultures of rat anterior pituitary cells were stimulated for 24 h with either hrIL1 beta, hrIL1 alpha or hrTNF alpha alone or with the addition of dexamethasone or indomethacin. The culture media were analyzed for ACTH, PGE2 and cAMP content. At doses ranging from 0.03 to 30 nM, hrIL1 beta stimulated the release of ACTH and PGE2 in a dose-dependent manner. In contrast, at doses ranging from 3 to 60 nM, hrTNF alpha was unable to stimulate ACTH secretion although it stimulated PGE2 synthesis. Time-course experiments demonstrated that hrIL1 beta (3 nM) stimulates ACTH production over a period of 8, 16 and 24 h, but not after a period of 4 h. In these experiments, hrIL1 beta failed to cause any change in the secretions of growth hormone and luteinizing hormone.(ABSTRACT TRUNCATED AT 250 WORDS)     

Inhibitors of interleukin 1 activity in synovial fluids and in cultured synovial fluid mononuclear cells.

Measurement of interleukin 1 (IL-1) in synovial fluids (SF) yielded variable results and implied the presence of an inhibitory activity. As peripheral blood monocytes produce an IL-1 receptor antagonist (IL-1ra), we investigated whether SF mononuclear cells (SFMC) also secreted such inhibitory activity. MC isolated from inflammatory SF produced, in addition to variable levels of IL-1, a specific IL-1 inhibitor of approximately 23 kDa which blocked both IL-1 biological activity and binding to its receptor. Western blot, using a polyclonal antibody to rhIL-1ra, indicated that SFMC secreted material that shared immunological crossreactivity with the cloned IL-1ra. IL-1 inhibitory activity was also detected in SF but not formally demonstrated to be related to IL-1ra. In conclusion, SFMC could produce IL-1ra and an imbalance between IL-1 and its specific antagonist may be relevant to the severity of joint destruction.