Direct contact with stimulated T cells induces the expression of IL-1beta and IL-1 receptor antagonist in human monocytes. Involvement of serine/threonine phosphatases in differential regulation.

Imbalance in the production of cytokines and their inhibitors plays a part in inflammation in chronic destructive diseases. Direct cell-cell contact with stimulated T cells markedly induces the production of pro-inflammatory cytokines and matrix metalloproteinases in monocytes. This study demonstrates that direct contact with stimulated T cells favours the production of IL-1beta over that of IL-1 receptor antagonist (IL-1Ra) in both peripheral blood monocytes and the monocytic cell line THP-1. In contrast, soluble factors secreted by stimulated T cells favour the production of IL-1Ra. Differentiation of THP-1 cells with 1,25-(OH)2D3 did not affect the balance between IL-1beta and IL-1Ra production, enhancing both cytokines 2.3- and 1.6-fold, respectively. Among different inhibitors of phosphorylation and dephosphorylation processes, only okadaic acid, an inhibitor of serine/threonine phosphatases, differentially modulates the production of IL-1beta and IL-1Ra. Indeed, okadaic acid upregulated IL-1beta and decreased IL-1Ra at the mRNA and protein level in monocytic cells activated by membranes of stimulated T cells. These results suggest that serine/threonine phosphatases play a part in the differential regulation of the production of IL-1beta and IL-1Ra by monocytes upon direct cell-cell contact with stimulated T cells. This mechanism may regulate the balance between the pro-inflammatory cytokine and its inhibitor, which balance dictates in part the outcome of the inflammatory process.

Expression and cleavage of tumor necrosis factor-alpha and tumor necrosis factor receptors by human monocytic cell lines upon direct contact with stimulated T cells.

Tumor necrosis factor-alpha (TNF-alpha) is a potent cytokine in inflammatory processes. A variety of mechanisms that modulate its activity have been described, one being its binding to soluble receptors (sTNFR). In this study, we demonstrate that human monocytic cells such as THP-1 respond to direct contact with a membrane preparation of stimulated HUT-78 cells by producing TNF-alpha and by releasing sTNFR-p75, but not sTNFR-p55, with different kinetics. TNF-alpha concentration peaked after 12 h of contact and then decreased, whereas sTNFR-p75 production increased progressively upon cell/cell contact. The decrease in TNF-alpha concentration is not due to trapping of TNF-alpha by its soluble receptors or other soluble or cell-associated molecules, but rather to a proteolytic activity associated to THP-1 cells. On the other hand, the increase in sTNFR-p75 release does not result from an increase in the cleavage of pre-existing cell-associated sTNFR-p75 but from an increase in TNFR-p75 expression, immediately followed by the cleavage of its extracellular domain. Phenylmethylsulfonylfluoride, a serine protease inhibitor, has a negative effect on both TNF-alpha degradation and sTNFR-p75 release by THP-1 cells. Thus, there may be an enzymatic activity associated to THP-1 cells that plays an important role in the neutralization of TNF-alpha activity both by degrading the molecule and by cleaving its receptors at the cell surface.

Direct contact between T lymphocytes and monocytes is a major pathway for induction of metalloproteinase expression.

Monocytes and macrophages can modulate the turnover of extracellular matrix by producing metalloproteinases such as interstitial collagenase and 92-kDa gelatinase as well as tissue inhibitor of metalloproteinases. To study mechanisms of metalloproteinase induction in human mononuclear phagocytes, the effects of direct cell-cell contact between activated T lymphocytes and the human monocytic cell line THP-1 were determined. T cells were first activated with phorbol 12-myristate 13-acetate and phytohemagglutinin for 24 h, fixed with paraformaldehyde, and then exposed to THP-1 cells for 48 h. Upon contact with fixed activated T lymphocytes, a massive induction in the expression of both proteinases and tissue inhibitor of metalloproteinases was observed, whereas unstimulated T cells had no effect. Stimulation of metalloproteinase biosynthesis by THP-1 cells was mimicked by a membrane preparation derived from activated T cell lines, whereas cytosol and nuclear fractions of the T cells were ineffective. Furthermore, activated T lymphocytes exposed to trypsin, tunicamycin, or cycloheximide lost the capacity to stimulate THP-1 cells upon subsequent contact, implying the involvement of cell-surface glycoproteins. Similar induction of metalloproteinases by direct contact with activated T cells was also observed using normal blood monocytes as the target cells, and stimulation of monocyte metalloproteinases by T cell contact occurs at a pretranslational level. Consequently, cell-cell contact may represent an important biological mechanism for potentiating the inflammatory response that leads to extracellular matrix destruction.

Cell surface glycoproteins expressed on activated human T cells induce production of interleukin-1 beta by monocytic cells: a possible role of CD69.

In many immunoinflammatory diseases, macrophages, by producing interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF alpha), stimulate protease secretion in fibroblasts, thus contributing to tissue destruction. Monocyte/macrophage activation is prompted by soluble factors released by activated T cells as well as by cell-cell contact. Indeed, previous studies have shown that monocytes exposed to paraformaldehyde (PFA)-fixed, activated T cells produced high amounts of IL-1 beta. In this report, we used the T cell line HUT-78 to further characterize the T cell factor(s) responsible for monocyte activation by cell-cell contact. After subcellular fractionation, most of the activity was found in the cellular membrane fraction of PHA/PMA-stimulated HUT-78 cells, and proved to be due to glycoproteins, following trypsin digestion and tunicamycin treatment. HUT-78 cells acquired the capacity to stimulate monocytic cells after as little as 1h of stimulation. De novo protein synthesis was required for the expression of the IL-1 beta inducing factor, as shown by cycloheximide treatment. When membrane proteins of PHA/PMA-stimulated HUT-78 cells were separated on SDS-polyacrylamide gel, a peak of stimulatory activity was observed at Mr--25-35 x 10(3). By using specific cytokine inhibitors or blocking mAbs, we ascertained that cell-associated cytokines (IL-1, IL-2, IFN gamma and GM-CSF) were not involved in monocyte activation by cell contact. Anti-CD2 and -CD11a (LFA-1) mAbs partially blocked IL-1 beta production by -25% and -35%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacoeconomic comparison of cyclosporine oral solution and capsules after kidney transplantation.

We studied 20 kidney transplant recipients who had received Sandimmune cyclosporine A (CSA) capsules for an average of 7.9 months at a mean dose of 312 mg/day. They were switched to CSA liquid in the same dosage for an average of 15.5 months. There was no significant difference between the means for the monthly values of either serum creatinine or whole blood CSA when the periods on capsules and liquid were compared. Fourteen bottles from 4 batches with volume stated as 50 ml CSA actually contained an average of 53.7 ml. Comparison of the amount of capsules and liquid CSA prescribed and the amount dispensed by the pharmacy showed that the amount neglected (prescribed > dispensed) was similar for patients on liquid and capsules. Wastage (prescribed < dispensed) was about 5% greater when on liquid, and as our cost for liquid was 18% less than for capsules, we saved about 13% by use of the liquid.

IFN-gamma and 1,25(OH)2D3 induce on THP-1 cells distinct patterns of cell surface antigen expression, cytokine production, and responsiveness to contact with activated T cells.

Differentiation and maturation of monocytes are accompanied by the expression of specific surface glycoproteins, the secretion of cytokines, and the capacity to respond to ligands. These changes may be influenced by interactions with hormones, soluble lymphocytic products, or direct contact with lymphocytes. We have studied two distinct pathways in the differentiation of a human monocytic cell line, THP-1: one being induced by IFN-gamma and the other by 1 alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3). In THP-1 cells, IFN-gamma induces cell surface expression of HLA-DR and CD54 and production of IL-1 beta, TNF-alpha, and IL-6. In contrast, 1,25(OH)2D3 increases cell surface expression of CD11b and CD14, but fails to stimulate cytokine production. Direct contact of THP-1 with stimulated fixed T cells markedly induces IL-1 beta, TNF-alpha, and IL-6 production by THP-1. Production is higher when THP-1 have been previously exposed to 1,25(OH)2D3 as compared to prior exposure to IFN-gamma. mAb raised against certain relevant cell surface glycoproteins on THP-1 were tested for their ability to block the response of THP-1 to T cells. Antibodies to CD11a, CD11b, and CD11c, alone or in combination, only partially blocked IL-1 beta production by THP-1, whereas antibodies to CD54 and CD14 did not. Thus other unknown structures on the THP-1 cells may be involved in the induction of THP-1 cytokine production by T cell contact.

Tumor necrosis factor inhibitor: purification, NH2-terminal amino acid sequence and evidence for anti-inflammatory and immunomodulatory activities.

The urine of some febrile patients has been shown to contain a tumor necrosis factor-alpha-inhibiting activity (TNF-alpha INH) when tested in a cytotoxicity assay using the TNF-susceptible cell line L-929. The inhibitor was purified to homogeneity using a simple three-step procedure which included a TNF-alpha affinity column, cation exchange and reverse-phase chromatography. The NH2-terminal amino acid sequence of the inhibitor showed no sequence similarity with proteins in the data bases used. Using gel filtration, it was shown that TNF-alpha and the inhibitor form a stable complex which eluted with a molecular weight of about 75,000. This value corresponds to the sum of the inhibitor (approximately 30,000) and TNF-alpha (approximately 45,000-50,000) molecular weight. The TNF-alpha INH blocked prostaglandin E2 production by dermal fibroblasts in a dose-dependent manner, providing evidence for antiinflammatory activity. TNF-alpha INH also blocked class I antigen expression in a dose-dependent manner as measured using the human Colo 205 tumor cell line. Furthermore, TNF-alpha INH affected TNF-alpha synergism with IFN-gamma-induced HLA-DR antigen expression but had no effect on IFN-gamma activity. The data presented demonstrate that TNF-alpha bioactivity can be regulated at the protein level.

Range measurements by a mobile robot using a navigation line.

A continuous, straight-edged line is used for the visual navigation of an autonomous mobile robot in a factor environment. This line, which resides on the floor and contrasts with background, may also be used to determine range information. Two methods are developed for determining the range of an object in the sensor's field of view. The effects of various error conditions in the system geometry on each ranging method are determined. Equations are derived which yield the percent error in calculating ranges given estimates of these error conditions. Numerical examples using typical sensor parameters are given.

Electroretinographic testing in diabetics: a comparison study of the Burian-Allen and the Henkes corneal electrodes.

A series of 57 diabetics underwent standard electroretinographic recordings for the purpose of testing the effect of insulin on the electroretinograms in diabetes mellitus, specifically on the oscillatory potential changes (Kozak et al., Jap. J. Ophthal. Suppl., 1979). Use of the speculum-type corneal electrode (Burian-Allen, Hansen Labs.,) produced 9 corneal abrasions in the first 28 patients in this series. However, when the technique of examination was altered by use of the Henkes-type bipolar electrode, only 2 abrasions were produced in the last 29 patients. These frequencies of abrasions are statistically different. The suggestion is made that electroretinographic tracings in diabetics the performed with the use of the Henkes bipolar low-vacuum corneal electrode (Medical Workshops, Holland).