CD45 isoform expression during T cell development in the thymus

Abstract

Various isoforms of leukocyte common antigen, or CD45, are expressed differentially on T cells at different stages of development and activation. We report studies on CD45 isoform expression on various subsets of human T cells using two- and three-color flow cytometry and cell depletion. Bone marrow cells that were depleted of CD3+ and HLA-DR+ cells were CD45RA-RO-. The earliest CD3-CD4-CD8-CD19- thymocytes were CD45RO- with 20%-30% CD45RA+ cells. The most prominent population of CD4+CD8+ double-positive thymocytes were CD45RA-RO+. Even the CD4+CD8+ blasts were greater than 90% CD45RO+. About 80% of single-positive thymocytes (CD4+CD8- or CD4-CD8+) were also CD45RO+. Only 4.3% of CD4+ and 18% of CD8+ single-positive thymocytes were CD45RA+. In contrast, cord blood T cells which represent the stage that immediately follows single-positive thymocytes, contained 90% CD45RA+ cells. Thus, in terms of CD45 isoform expression, single-positive thymocytes are more like double-positive cells than cord blood T cells. These results suggest the following sequence of CD45 isoform switching during T cell development: CD45RA-RO- or RA+RO- (double-negative thymocytes)----RA-RO+ (double-positive and most single-positive thymocytes)----RA+RO- (cord blood T cells), the last switch from CD45RO to CD45RA occurring as a final step of maturation in the thymus.

Prophylactic ciprofloxacin treatment prevented high mortality, and modified systemic and intestinal immune function in tumour-bearing rats receiving dose-intensive CPT-11 chemotherapy

“…We also observed a preponderance of activated T cells (increased percentages of CD45RAÀ, CD71, CD25 and decreased percentage of CD62L in CD4 þ and CD8 þ T cells) after CPT-11. Antigen-naive T cells are characterised phenotypically by CD45RA (high-molecular-weight isoform of CD45), and the peripheral lymph node homing receptor, CD62L (L-selectin) (Fujii et al, 1992;Bradley et al, 1994). When naive T cells are stimulated, their cell surface phenotype undergoes a number of changes.…”

Osteopenia in X-linked hyper-IgM syndrome reveals a regulatory role for CD40 ligand in osteoclastogenesis

“…Antigen priming of T cells is associated with a change in the T cell CD45 isoform: human naïve T cells express the CD45RA isoform, whereas antigen-primed human memory T cells express the CD45RO isoform (29). We evaluated the expressions of CD45 isoforms by the CD4 ϩ T cells of 13 patients with XHIM and compared them with age-matched controls by flow cytometry.…”

Defects of T-cell effector function and post-thymic maturation in X-linked hyper-IgM syndrome

“…In humans, antigen priming of T cells is associated with a change in T-cell CD45 isoform expression (27). Naive T cells express the CD45RA isoform, whereas antigen-primed (memory) T cells express the CD45RO isoform (28,29). Given the occurrence of T-cell priming defects in CD154 knockout mice (30), as well as the evidence of cytokine production deficiency in the patients discussed here, we evaluated the expression of the CD45 isoforms by the T cells of patients with…”