Age-Dependent Metabolic and Immunosuppressive Effects of Tacrolimus.

Immunosuppression in elderly recipients has been underappreciated in clinical trials. Here, we assessed age-specific effects of the calcineurin inhibitor tacrolimus (TAC) in a murine transplant model and assessed its clinical relevance on human T cells. Old recipient mice exhibited prolonged skin graft survival compared with young animals after TAC administration. More important, half of the TAC dose was sufficient in old mice to achieve comparable systemic trough levels. TAC administration was able to reduce proinflammatory interferon-γ cytokine production and promote interleukin-10 production in old CD4+ T cells. In addition, TAC administration decreased interleukin-2 secretion in old CD4+ T cells more effectively while inhibiting the proliferation of CD4+ T cells in old mice. Both TAC-treated murine and human CD4+ T cells demonstrated an age-specific suppression of intracellular calcineurin levels and Ca2+ influx, two critical pathways in T cell activation. Of note, depletion of CD8+ T cells did not alter allograft survival outcome in old TAC-treated mice, suggesting that TAC age-specific effects were mainly CD4+ T cell mediated. Collectively, our study demonstrates age-specific immunosuppressive capacities of TAC that are CD4+ T cell mediated. The suppression of calcineurin levels and Ca2+ influx in both old murine and human T cells emphasizes the clinical relevance of age-specific effects when using TAC.

Comparative evaluation of non-radioactive in situ hybridization techniques for pathologic diagnosis of viral infection.

We have compared the efficiency of biotinylated DNA probes and various visualization techniques with 35S-labeled DNA probes in routine paraffin sections from the pathology service; both autopsy and biopsy tissue were investigated. Probes included DNA genomic fragments from cytomegalovirus (CMV), Epstein-Barr-Virus (EBV) and human immunodeficiency virus (HIV). Methods of detection by Pathogene II kit (ENZO) and Blue Gene kit (BRL) with visualization by AEC, NBT/BCIP, Immunogold (Janssen) and autoradiography were used. The study shows most satisfactory results by applying the Blue Gene-NBT/BCIP combination followed by the Immunogold technique. Data obtained by these techniques compare well to those of using radioactive DNA probes and autoradiography.