Reversal of T cell anergy in leprosy patients: in vitro presentation with Mycobacterium leprae antigens using murabutide and Trat peptide in liposomal delivery.

Mycobacterium leprae, the causative agent of leprosy resides and multiplies within the host monocytes and macrophages, thereby evading host immune system. Cell-mediated immune response (CMI) plays a vital role as evidenced from the high CMI in BT/TT (borderline and tuberculoid) patients and conversely low in BL/LL (borderline and lepromatous) patients. In the present study, an attempt was made to immunomodulate the anergized T cells of lepromatous leprosy patients by presenting the mycobacterial antigen in combination with T cell adjuvant, murabutide (active analog of muramyl' dipeptide, MDP-BE) and a Trat peptide (T cell epitope of Integral membrane protein (Trat) from Escherichia coli) in particulate form (liposomes) or soluble form (media). PBMNC of normal, BT/TT and BL/LL were stimulated in vitro with five mycobacterial antigens (Ag) in the following formulations, Ag, Ag+murabutide, Ag+murabutide+Trat peptide either in liposomes or in medium. All the five antigen(s) when delivered in liposomes containing murabutide and Trat peptide showed a very high lymphoproliferative response (p<0.001) in all the three groups. IFN-gamma and IL-2 were significantly (p<0.001) high in these culture supernatants compared to IL-10 and IL-4 confirming a shift from CD4+Th2 to Th1 response in leprosy patients with particulate mode of antigen presentation. Interestingly, PBMNC derived from lepromatous patients also showed consistent T cell proliferation with all the formulations. Further, the mechanism of liposomal processing of antigens was studied using different inhibitors that interfere at different stages of antigen presentation. Results indicate that this study may pave way for an immunotherapeutic approach for reverting the anergic T cells of lepromatous patients to proliferating T cells with the release of Th1 cytokines thereby restoring the CMI response in these patients.

Solvation of dried dentin matrix by water and other polar solvents.

PURPOSE: To develop a simple method for measuring the degree of solvation of dried, demineralized dentin matrix by water and other polar solvents. The null hypothesis was that there are no differences in expansion forces produced by different polar solvents. MATERIALS AND METHODS: Midcoronal dentin discs were prepared from extracted, unerupted human third molars. The discs were cut into square specimens with surface areas of 2 x 2, 3 x 3 and 4 x 4 mm and thicknesses of 0.5, 1.0 and 1.5 mm. After demineralization in 0.5 M EDTA (pH 7), the dimensions of the specimens were measured both wet and dry. Dry specimens were held between two parallel steel plates connected to a 50 N load cell which measured the solvation force when water or other polar solvents were added. After measuring the expansion force induced by water, the specimens were fixed in glutaraldehyde and the trials repeated. On additional specimens, repeated measures of expansion forces were obtained using water, methanol, ethanol, n-propanol, n-butanol, ethylene glycol, formamide, hydroxyethylmethacrylate, N,N-dimethyl formamide and acetone in unfixed specimens. RESULTS: Water produced hydration forces as high as 204 g before, and 428 g after glutaraldehyde treatment. The hydration force correlated better with specimen thickness than with surface area. Water solvated the matrix faster than methanol > ethanol > formamide > ethylene glycol. Hydroxyethylmethacrylate, N,N-dimethyl formamide and acetone were unable to solvate the dried matrix. Regression analysis of solvation force vs. Hansen's solubility parameters for dispersive, polar and hydrogen bonding forces demonstrated that solvation force correlations were highest with hydrogen bonding solubility parameters. Measurements of solvation forces provides a simple method for determining solvent-collagen matrix interactions.

Thalidomide costimulates primary human T lymphocytes, preferentially inducing proliferation, cytokine production, and cytotoxic responses in the CD8+ subset.

The efficacy of thalidomide (alpha-phthalimido-glutarimide) therapy in leprosy patients with erythema nodosum leprosum is thought to be due to inhibition of tumor necrosis factor alpha. In other diseases reported to respond to thalidomide, the mechanism of action of the drug is unclear. We show that thalidomide is a potent costimulator of primary human T cells in vitro, synergizing with stimulation via the T cell receptor complex to increase interleukin 2-mediated T cell proliferation and interferon gamma production. The costimulatory effect is greater on the CD8+ than the CD4+ T cell subset. The drug also increases the primary CD8+ cytotoxic T cell response induced by allogeneic dendritic cells in the absence of CD4+ T cells. Therefore, human T cell costimulation can be achieved pharmacologically with thalidomide, and preferentially in the CD8+ T cell subset.

Application of solubility parameter theory to dentin-bonding systems and adhesive strength correlations.

The principal aim of this study was to investigate the relationships between the solubility parameters of ectched dentin, and adhesive primer solutions and adhesive bond strength. Solubility parameters characterize the molecular interactions which determine physical properties such as wetting, and thus can serve as tools to aid development of polymeric adhesives and interpenetrating polymer networks. If an adhesive monomer has a solubility parameter close to that of a polymer substrate, then the monomer may act as a solvent for the polymer and penetrate below the surface. Subsequent polymerization of the monomer may then produce an interpenetrating network, thus adhering without necessarily forming primary chemical bonds to the substrate. The dentin substrate considered in this study was abraded dentin treated with ethylenediaminetetraaceitc acid. Solubility parameters delta pr, delta h, and delta d calculated for the etched dentin substrate were 20.3, 23.6, and 16.0 (J/cm3)1/2, respectively. Solubility parameters of the primers were expressed using Hansen's three-dimensional scheme. The data indicate a correlation between the calculated solubility parameters of the etched dentin, and dentin primers and the resulting bond strengths. The results corroborate the significance of solubility parameter considerations for adhesive bonding to dentin.

Protection of mice against mycobacterial infection by lymphoid cell vaccination.

Intracellular parasites may thrive by inducing the host's immune system to suppress the effector immune response that otherwise limits multiplication. Hosts are traditionally immunized with the parasite antigens that induce effector immunity. Alternatively, one might vaccinate the host with the host lymphoid cells involved in suppression. Multiplication of Mycobacterium marinum was prevented by vaccinating mice with cells prepared from the popliteal lymph nodes of mice in which the organisms were multiplying logarithmically, that were inactivated by fixation with glutaraldehyde. Cells obtained later during infection, when the donor mice manifest immunity, did not protect against infection. Thus, it may be possible to influence the course of a microbial infection by immunizing the host not only with components of the organisms, but also with the host components that are exploited by the organism.

Use of glutaraldehyde for disinfection in dialysis.

We compared Cidex HD Disinfecting Solution (CHD), a brand of glutaraldehyde disinfectant, alone and with bleach (B) to formaldehyde (F) with bleach for disinfection and cleaning of hemodialysis equipment. Two Drake-Willock central delivery systems (CDS) with 15 accompanying bedside stations and one Drake-Willock 4216 single patient delivery system (SPS) were used. The CDS designated #1, delivered dialysate to bedside stations 1 through 9, while CDS#2 supplied bedside stations 10 through 16. The study was conducted in three stages. Stage I used F six nights per week and B cleaning Wednesday (CDS#1/SPS) versus F Monday, Wednesday, and Friday with B on Wednesday (CDS#2) for four weeks. Stage II compared CHD six nights/week versus CHD Monday, Wednesday, and Friday for eight weeks. Stage III compared CDH six nights/week with B cleaning on Wednesday versus CHD on Monday, Wednesday, and Friday with B cleaning on Wednesday for four weeks. Samples of pretreated water were collected aseptically on Mondays, Wednesdays, and Fridays each week from the following sites: pre/CDS, inflow Hansen-bedside stations #5, #13, and SPS and pre-blood detector on BS #5, #13, and the SPS. During the study, 763 samples were cultured. Microbiological test results were reported as colony forming units per ml (CFU/ml). The CFU/ml were obtained by filtrating a 10 ml aliquot through a 0.45 mu filter, the filter transferred to a petri dish containing standard plate count agar and counted.(ABSTRACT TRUNCATED AT 250 WORDS)