Publication Date:
2009-10-29
Description:
Estimates of precursor frequency and assessment of functional characteristics of alloreactive CD4+ T cells are all biased by the need for long-term culture. In this study, direct visualization of human alloreactive CD4+ T cells on the single-cell level was achieved using cell surface expression of CD154 as a tool for identification. The average frequency of alloreactive CD154+CD4+ T cells among peripheral blood CD4+ T cells was 0.1%, with half of the cells displaying a naive phenotype. The proliferation capacity and expression of cytokines after allogeneic stimulation resided in these CD154+CD4+ T cells. The repertoire of alloreactive CD4+ T cells was biased to a Th17 response, and on average 24% of alloreactive CD154+CD4+ memory T cells produced interleukin-17 (IL-17) after polyclonal stimulation. Unexpectedly, mixed cell cultures from human leukocyte antigen (HLA)–identical donors also generated alloreactive CD154+CD4+ T cells and yielded the highest frequency compared with HLA-nonidentical combinations. Therefore, reactivity to minor histocompatibility antigens between HLA-identical subjects appears to be relatively common. Alloreactive HLA-identical T cells did not proliferate or express cytokines, but were driven to proliferation in the presence of exogenous IL-2.
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
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