Incomplete effector/memory differentiation of antigen-primed CD8+ T cells in gene gun DNA-vaccinated mice

DNA vaccination is an efficient way to induce CD8+ T cell memory, but it is still unclear to what extent such memory responses afford protection in vivo. To study this, we induced CD8+ memory responses directed towards defined viral epitopes, using DNA vaccines encoding immunodominant MHC class I-restricted epitopes of lymphocytic choriomeningitis virus covalently linked to beta2-microglobulin. This vaccine construct primed for a stronger recall response than did a more conventional minigene construct. Despite this, vaccinated mice were only protected against systemic infection whereas protection against the consequences of peripheral challenge was limited. Phenotypic analysis revealed that DNA vaccine-primed CD8+ T cells in uninfected mice differed from virus-primed CD8+ T cells particularly regarding expression of very-late antigen (VLA)-4, an adhesion molecule important for targeting T cells to inflammatory sites. Thus, our DNA vaccine induces a long-lived memory CD8+ T cell population that provides efficient protection against high-dose systemic infection. However, viral replication in solid non-lymphoid organs is not curtailed sufficiently fast to prevent significant virus-induced inflammation. Our results suggest that this is due to qualitative limitations of the primed CD8+ T cells.     

Interference of hydroxocobalamine treatment on commun biochemical determinations

Hydroxocobalamin, antidote of the cyanide poisoning, is a red and water soluble pigment, which colors biological mediums. The interferences caused by this molecule are studied for plasma pools overloaded with hydroxocobalamin for concentrations from 0 to 1,125 mg.L-1. The results of 16 biochemical parameters on Vitros 750 XRC (Ortho-clinical Diagnostics) and of 23 biochemical parameters on Cobas Integra 700 (Roche Diagnostics) are examined. With this analytical system, unconjugated and conjugated bilirubin, creatinin, and CK results are changed as soon as plasma concentration of hydroxocobalamin reachs 124 mg.L-1. For the Vitros 750 XRC, ASAT, iron, creatinin, phosphorus are more sensitive to this interference. But, other results are changed for the two analytical systems for superior hydroxocobalamin concentrations.