3 research outputs found
Evolution of a CD3+/CD+ α/ β T-Cell Receptor+ Mature T-Cell Clone from CD3-CD7+ Sorted Human Bone Marrow Cells
In order to study extrathymic differentiation in vitro, CD7+CD3- lymphocytes were
sorted from normal human bone marrow and cultured under conditions of limiting
dilution together with irradiated pooled allogeneic peripheral blood mononuclear cells
(PBMC) and phytohemagglutinin (PHA) in the presence of 1000 U/ml of interleukin-2
(IL-2). One clone was obtained that failed to react with monoclonal antibody (mAb)
TCRδ1 (TCRγ/δ-specific) or WT31 (TCR2, α/β-specific). From day 35 through day 74
in culture, the surface phenotype of this clone evolved into CD3+, CD4+, CD8-, TCR2+,
TCR1-, and was further characterized as CD2+, CD45RO+, CD16-, and CD56-. The presence
of mRNA for TCR α and γ but not ,and γ chains was confirmed by Northern blotting.
Accessory cell-dependent autocrine proliferative responses to PHA (most likely
driven by IL-2) were initially absent, but became measurable at the same time as the
TCR was acquired. However, in the absence of PHA, the clone failed to respond to a
panel of homozygous B-cell lines representing the majority of MHC class II alleles.
Autoreactivity was also not demonstrable. Cytotoxicity was limited to MHC unrestricted
“natural killer (NK)-like” lysis of K562 target cells, with no autocytotoxicity
detected. Tle NK-like lysis diminished over time in parallel with the acquisition of surface
TCR. The cloned cells were not suppressive for mature lymphocyte proliferation.
After stimulation, the cells secreted tumor necrosis factor α and
granulocyte/macrophage colony-stimulating factor (GM-CSF) detected by immunoassays,
and T-cell growth factors, most likely IL-2, as detected by bioassays. Polymerase
chain-reaction methods demonstrated the presence of mRNA for IL-2, IL-3, IL-4, IL-9,
interferon-δ, and GM-CSF in these cells after stimulation with PHA and B-LCL