Responses to human rhinovirus in CD45 T cell subsets isolated from tonsil

Abstract

Isotypes of CD45 have been used extensively as markers of memory and naive populations of T cells in peripheral blood. In this study, T cells were isolated from human tonsil and their proliferative response against human rhinovirus was measured. Unexpectedly, equivalent responses were found among the CD4 + CD45RA + and CD4 + CD45RO + populations of T cells. This response requires MHC class II-positive antigen-presenting cells. The time course of the T cell response in vitro was that of a classical recall response, and no proliferative response to the virus could be detected in human cord blood. These results suggest that tonsils contain a significant population of CD45RA + memory cells. The presence of this population may reflect ongoing stimulation with this common infectious agent, and the anatomical location of the T cells within the major lymphoid organ draining the naso-pharyngeal epi-thelial surface.

Qualitative differences between naïve and memory T cells

“…56,57 Likewise, some primed CD45RA + CD4 + T cells can be found under conditions of chronic antigen exposure. 45 Whether the CD45RA + cells observed in these studies have in fact re-expressed this molecule is unclear. Another possibility is that some cells may retain expression of CD45RA under certain conditions of activation.…”

“…These cells, which also express low levels of CD28 and CD27, appear to arise from chronic antigenic stimulation 56,57 . Likewise, some primed CD45RA + CD4 + T cells can be found under conditions of chronic antigen exposure 45 …”

“…In addition to CD62L and CCR7, memory T cells may express other markers associated with naïve T cells, such as high-MW isoforms of CD45. 16,17,[39][40][41][42][43][44][45][46] In some instances, it is evident that expression of a 'naïve' phenotype by primed cells represents phenotypic reversion. This has been shown to be the case for CD62L, CCR7 and high-MW isoforms of CD45, each of which can be re-expressed by cells that were formerly negative for these markers.…”

“…These cells have been termed ‘central memory’ and ‘effector memory’ cells, respectively, based on their expression of lymph node homing molecules and their functional properties (see below). In addition to CD62L and CCR7, memory T cells may express other markers associated with naïve T cells, such as high‐MW isoforms of CD45 16,17 , 39–46 …”

Transcription Factor Early Growth Response 3 Is Associated with the TGF-β1 Expression and the Regulatory Activity of CD4-Positive T Cells In Vivo

“…When T cells isolated from human tonsils were examined according to their CD45 expression, naive type tonsillar T cells (CD4 + CD45RA + ) were found to proliferate at a similar rate to memory type tonsillar T cells (CD4 + CD45RO + ) after rhinovirus stimulation (44). Continuous stimulation with an infectious agent might lead to the chronic activation of tonsillar T cells.…”