Increase in PD-1+ CD4+ T cells during ageing and in development of AML.

<p>(A) Spleen cells from 2 months old and 14 months old mice were stained with antibodies against CD4 and PD-1. (B) Quantification of the data in (A) is presented as mean +/− SD, (young: n = 3, old: n = 7). (C) PD-1- CD4+ and PD-1+ CD4+ splenic T cells from 14 months old mice were analyzed for expression of <i>Cebpa</i> normalized to <i>β-actin</i> by qRT-PCR. Data are presented as mean +/− SEM, (n = 7). (D) Spleens from 3 months old mice were stained for CD4, PD-1, CD44 and CD62L. A representative example is shown (n = 5). (E) The spleens from healthy (age-matched, non-transplanted) and leukemic mice were analyzed for PD-1+ CD4+ T cells. **P<0.01; n.s.: not significant.