Covalent enzyme coupling on cellulose acetate membranes for glucose sensor development

International audienceMethods for immobilizing glucose oxidase (GOx) on cellulose acetate (CA) membranes are compared. The optimal method involves covalent coupling of bovine serum albumin (BSA) to CA membrane and a subsequent reaction of the membrane with GOx, which has previously been activated with an excess of p-benzoquinone. This coupling procedure is fairly reproducible and allows the preparation of thin membranes (5-20 µm) showing high surface activities (1-3 U/cm2) which are stable over a period of 1-3 months. Electrochemical and radiolabeling experiments show that enzyme inactivation as a result of immobilization is negligible. A good correlation between surface activity of membranes and their GOx load is observed

Heat-Killed Trypanosoma cruzi Induces Acute Cardiac Damage and Polyantigenic Autoimmunity

Chagas heart disease, caused by the protozoan parasite Trypanosoma cruzi, is a potentially fatal cardiomyopathy often associated with cardiac autoimmunity. T. cruzi infection induces the development of autoimmunity to a number of antigens via molecular mimicry and other mechanisms, but the genesis and pathogenic potential of this autoimmune response has not been fully elucidated. To determine whether exposure to T. cruzi antigens alone in the absence of active infection is sufficient to induce autoimmunity, we immunized A/J mice with heat-killed T. cruzi (HKTC) emulsified in complete Freund's adjuvant, and compared the resulting immune response to that induced by infection with live T. cruzi. We found that HKTC immunization is capable of inducing acute cardiac damage, as evidenced by elevated serum cardiac troponin I, and that this damage is associated with the generation of polyantigenic humoral and cell-mediated autoimmunity with similar antigen specificity to that induced by infection with T. cruzi. However, while significant and preferential production of Th1 and Th17-associated cytokines, accompanied by myocarditis, develops in T. cruzi-infected mice, HKTC-immunized mice produce lower levels of these cytokines, do not develop Th1-skewed immunity, and lack tissue inflammation. These results demonstrate that exposure to parasite antigen alone is sufficient to induce autoimmunity and cardiac damage, yet additional immune factors, including a dominant Th1/Th17 immune response, are likely required to induce cardiac inflammation

Naturally occurring B-cell autoreactivity: A critical overview

In over one century of research in immunology marked progress in the scientific knowledge and the implications derived from it has been made. At the same time several contradictory and seemingly opposing results have been obtained. The term autoimmunity is still conceived by many as a term directly related to an immunopathological state. However, strong evidence exist that not only the immune system is able to recognize self-constituents, but it appears also that this property is essential for homeostasis. Direct or indirect alterations of such self-recognition properties of the immune system may contribute to pathology. In this review, the most recent advances in the field of naturally occurring B-cell autoreactivity in health as well as in disease are presented and discussed. © 2007 Elsevier Ltd. All rights reserved

Strain differences in the immune response of mice to horseradish peroxidase.

Hind footpads of mice of inbred strains were injected with horseradish peroxidase (PO) in Freund's complete adjuvant (FCA) and the response of the antibody-forming cells (AFC) in their popliteal lymph nodes was measured. Marked strain differences were found after the first injection and three types of responder strains were defined: high responders, with H-2(s), H-2(a) and H-2(b) haplotypes, low responders, with the H-2(d) haplotype and an intermediate type of responder, observed in mice of the H-2(k) and H-2(q) haplotypes. After a second injection of PO in FCA, strain differences in the response disappeared and all strains responded equally well. F(1) hybrids from high and intermediate or low responders gave a mean AFC response between the two parental responses. Immunoglobulin-forming cells (IFC) with no anti-PO function, appearing concomitantly with AFC in PO+FCA-immunized mice, were also counted. Compared with the IFC found in mice given FCA only, their number was always higher (two-five times more). The IFC response followed the same pattern as the AFC response and was high, intermediate and low in high, intermediate and low responders, respectively. The IFC:AFC ratio varied depending on how many days after the challenge it was measured, but was similar for all strains except the low responder strains, in which the ratio remained constant at approximately 1 throughout the immune response. Like the AFC response, the IFC counts in F(1) hybrids gave intermediate values, except in hybrids from the two low responders (BALB/c and DBA/2) in which there were five times more IFC than AFC. We concluded that PO responsiveness in mice seems to be under genetic control governed by the H-2 locus and by non-H-2 genes and that the IFC which appear concomitantly with AFC are under the same genetic control