Visualization, characterization, and turnover of CD8+ memory T cells in virus-infected hosts.

Abstract

SummaryThe cellular basis of T cell memory is a controversial issue and progress has been hampered by the inability to induce and to trace long-term memory T cells specific for a defined antigen in vivo. By using the murine model of lymphocytic choriomeningitis virus (LCMV) infection and an adoptive transfer system with CD8 § T cells from transgenic mice expressing an LCMV-specific T cell receptor, a population of authentic memory T cells specific for LCMV was generated and analyzed in vivo. The transferred transgenic T cells that have expanded (1,000-fold) and then decreased (10-fold) in LCMV-infected C57BL/6 recipient mice exhibited the following characteristics: they were (a) of larger average cell size than their naive counterparts but smaller than day 8 effector cells; (b) heterogeneous with respect to expression of cell surface "memory" markers; and (c) directly cytolytic when isolated from recipient spleens. The timedependent proliferative activity of these LCMV-specific memory T cells was analyzed in the recipients by bromodeoxyuridine labeling experiments in vivo. The experiments revealed that LCMV-specific CD8 + memory T cells can persist in LCMV-immune mice for extended periods of time (>2 mo) in the absence of cell division; the memory population as a whole survived beyond 11 too.

Virus-Specific CD8+ T Cells in the Liver: Armed and Ready to Kill

“…The Ag-primed CD8 ϩ T cells use specific T cell receptors to lyse infected cells presenting virus-derived peptides bound to MHC-class I molecules. Following the effector phase, T cell numbers contract and Ͼ90% of the total population is eliminated (1,2). The reduction in cell counts results from the withdrawal of survival factors, (3) and from increased levels of apoptotic signals that trigger activationinduced cell death (AICD).…”

Properties of murine CD8+CD27- T cells

“…The CD62L + CD44 low/+ phenotype is thought to represent the naive T cell population whereas CD62L dull CD44 bright and CD62L -CD44 bright phenotypes typify primed T cells [34]. In every compartment CD8 + CD27 -cells were completely excluded from the CD62L + CD44 low/+ (unprimed) T cell population.…”

Myeloid marker expression on antiviral CD8+ T cells following an acute virus infection

“…Peripheral blood was collected from euthanized mice via cardiac puncture and treated with 0.5 mM EDTA and stained with the appropriate mAb. Erythrocytes were lysed in 0.84% NH 4 Cl and washed twice with Iscove's modified Dulbecco's medium (BioWhittaker, Walkersville, MD) containing 10% FBS, 2 mM Lglutamine and antibiotics (complete medium). Aliquots were used for FACS analysis.…”

“…Subsequently, CD11b was demonstrated as an activation marker for CD8 + CTL during a virus infection [1]. Some reports have shown that CD11b expression becomes down-regulated when CD8 + T cells enter the memory phase, which could be used to phenotypically distinguish recently activated effectors cells from memory cells [4][5][6].…”