CD7‐negative T cells represent a separate differentiation pathway in a subset of post‐thymic helper T cells

Abstract

SUMMARYThe absence of CD7 protein and the corresponding mRNA is a stable feature in a subset of normal circulating CD4 memory T cells. It is still unresolved whether the CD7 ÿ subset represents a specific Tcell lineage. Here we show that repeated stimulation of highly purified CD4 CD45RA CD45RO ÿ naive T cells in vitro leads to the development of a distinct memory subset that is defined by the expression versus non-expression of the CD7 antigen. Comparing different T-cell activation pathways (TCR/CD3, CD2), we observed that alternative signals were critically involved in the development of CD4 + CD7 ÿ T cells. Peak mean numbers of CD7 ÿ memory cells occurred after 3-5 cycles of restimulation in vitro. Naive T cells that had undergone repeated stimulations were harvested and sorted into CD7and CD7 ÿ subsets. The vast majority (> 97%) of CD7 T cells retained their expression, whereas the CD7 ÿ population did not re-express the antigen during further propagation of separated Tcell subsets. In CD7 ÿ cells no CD7 mRNA was monitored, indicating transcriptional regulation of CD7 expression. Certain differentiation-related antigens, including the cutaneous lymphocyte antigen CLA, were preferentially expressed on CD7 ÿ T cells. We suggest that absence of CD7 expression in a subset of CD4 memory cells reflects a separate and stable differentiation state occurring late in the immune response. These T cells may represent the physiological counterpart of malignant T cells in certain forms of cutaneous T-cell lymphoma.

CD7 Is a Differentiation Marker That Identifies Multiple CD8 T Cell Effector Subsets

“…Although the CD7 high subset transiently up-regulated CD7 expression during in vitro stimulation, the CD7 low and CD7 neg subsets did not appear to re-express CD7 in vitro (data not shown). This is consistent with previous observations of the CD7 neg subset of CD4 T cells which were reported to represent a stable differentiation state occurring late in the immune response (15).…”

“…Interestingly, the CD7 neg population was mainly annexin V negative. This was also observed in the CD7 neg subset of the CD4 T cell population (data not shown) and is consistent with earlier studies reporting that CD7 neg CD4 T cells represent a stable population of cells which increases during aging, indicating a slow turnover and accumulation over time (15,39,40). A possible explanation for this phenomenon is that CD7 neg cells may avoid galectin-1-induced apoptosis (22,23,26).…”

Recent advances in pathogenesis and management of hypereosinophilic syndromes

“…However, no study to date has characterized adjacent infiltrating T-cells, leaving the question open whether the IL-5-producing T-cells display epidermotropic behavior, thereby inducing preferential eosinophil migration to skin. Although CD3 ) CD4 + cells have been shown not to express cutaneous lymphocyte antigen (unpublished observations), they consistently lack surface CD7 antigen, a characteristic of skin-homing T-cells (37). Interestingly, the principal target organs in this HES variant (i.e.…”

T cells and aging update February 1999

“…In human, most T cells are CD7+, but the frequency of CD7-negative cells increases with age (380) and although isolated T cell clones retain stable expression of their CD7-positive or negative phenotype (381), repeated stimulation and propagation of uncloned lines results in accumulation of CD7-negative cells in the CD4 but not CD8 subset (382). Increased proportions of CD7-negative cells are found in situations of chronic antigenic stimulation in vivo, eg.…”