In renal transplant, patients, the number of T cells expressing high levels of LFA-1 (LFA-1-bright) and of T cells expressing CD57 increases in response to viral infection, even if the latter is asymptomatic. Their role in long-term renal transplant patients with cytomegalovirus (CMV) antigenemia and concomitant transplant dysfunction was investigated. For this purpose, this study used triple-color flow cytometry, fluorescence-activated cell sorting of peripheral blood T cells (CD3+/LFA-1-dim or -bright and CD8+/CD57+ or CD57- subsets), and subsequent semiquantitative reverse transcription-polymerase chain reaction. Cytokine mRNA levels for interleukin (IL)-1 beta, IL-2, IL-4, IL-8, IL-10, tumor necrosis factor alpha, and interferon-gamma, as well as Granzyme A and IL-2R p55 and p75 transcripts were determined and compared in peripheral blood mononuclear cells and in separated T cell subsets. Although in patients with CMV infection and/or rejection, cytokine transcripts were readily detected and the levels in the CD3+/LFA-1-bright subsets were, by orders of magnitudes, higher than in the LFA-1-dim subset, hardly any cytokine message was found in patients without CMV infection or rejection episodes or in control subjects. The expression of Granzyme A, which is involved in cytotoxic T lymphocyte-mediated cytotoxicity, was not upregulated in LFA-1-bright T cells, which is in discordance with cytokine levels. Differences between CD57+ and CD57- T cells were limited to the IL-2R p55 mRNA, of which the former expressed significantly less than the latter. It is concluded that upon virus-induced activation of peripheral blood T cells, an effector type that is marked by high inflammatory but small cytotoxic potential is produced. The results of this study propose that these cells represent a correlate of persistent immune activation and are liable to produce graft dysfunction, although they are unable to clear the organism from virus infection because of their lack of cytotoxic potential.
Selective (Tacrolimus) FK506 Rescue Therapy Provides Stability for At-Risk Pediatric Renal Transplant Patients