Mycoplasma Contamination Revisited: Mesenchymal Stromal Cells Harboring Mycoplasma hyorhinis Potently Inhibit Lymphocyte Proliferation In Vitro

Mesenchymal stromal cells (MSC) have important immunomodulatory effects that can be exploited in the clinical setting, e.g. in patients suffering from graft-versus-host disease after allogeneic stem cell transplantation. In an experimental animal model, cultures of rat T lymphocytes were stimulated in vitro either with the mitogen Concanavalin A or with irradiated allogeneic cells in mixed lymphocyte reactions, the latter to simulate allo-immunogenic activation of transplanted T cells in vivo. This study investigated the inhibitory effects of rat bone marrow-derived MSC subsequently found to be infected with a common mycoplasma species (Mycoplasma hyorhinis) on T cell activation in vitro and experimental graft-versus-host disease in vivo.We found that M. hyorhinis infection increased the anti-proliferative effect of MSC dramatically, as measured by both radiometric and fluorimetric methods. Inhibition could not be explained solely by the well-known ability of mycoplasmas to degrade tritiated thymidine, but likely was the result of rapid dissemination of M. hyorhinis in the lymphocyte culture.This study demonstrates the potent inhibitory effect exerted by M. hyorhinis in standard lymphocyte proliferation assays in vitro. MSC are efficient vectors of mycoplasma infection, emphasizing the importance of monitoring cell cultures for contamination

FRIEDEL-CRAFTS ACYLATION ON POROUS DIVINYL BENZENE POLYMER PARTICLES - A REACTION KINETIC STUDY USING INFRARED SPECTROSCOPY

Author Institution: Agder College, Department of Chemistry; Department of Chemistry, University of Bergen; Department of Industrial Chemistry, Norwegian University of Science and Technology; Amersham Pharmacia Biotech AS, P.O. Box 213Porous poly(para-divinylbenzene) and poly(meta-divinylbenzene) particles were synthesised from para-divinylbenzene and meta-divinylbenzene monomers with toluene and 2-ethylhexanoic acid as porogens. The residual vinyl groups in the particles were thereafter reacted with lauroyl chloride using the Friedel-Crafts reaction. The conversion of vinyl groups was followed by analysing polymer particles taken from the reaction mixture at different time intervals. Infrared spectroscopy both in the mid and near infrared region was used as the analytical technique. The intensity changes in the overtone absorption at 1628 nm due to the vinyl bonds was used as the basis for the quantification of the reaction. Spectra of the particles in the mid IR region provide understanding of the changes taking place in the polymer matrix during the acylation reaction. The results indicated that the reaction took place at a faster rate in the polymer particles synthesised from para-DVB monomer compared with the poly(meta-DVB) particles. The polymer particles synthesised with toluene as porogen react faster than the polymer particles prepared with 2-ethylhexanoic acid as the porogen. The analysis also indicated that the acylation takes place at the early stages of the reaction and the product formed transforms into more stable products at the latter stages. Based on the infrared analysis, mechanisms for the formation of the different products are proposed