Fig 1: Thymus recovery in recipients given Stat3-/- transplants is associated with reduced PSGL-1loCD4+ T-cell infiltration in the thymus. BALB/c recipients were conditioned with 850 cGy TBI and given 2.5 × 106 TCD-BM plus 1 × 106 splenocytes from either WT or CD4-Stat3-/- C57BL/6 donors. a, b 10 days (a) and 30 days (b) after HCT, thymus specimens were harvested and stained with CK8 for the cortex and UEA-1 for the medulla epithelial cells. Percentage of CD4+CD8+ thymocytes was measured with flow cytometry. c Ten days after HCT, spleen and thymus were harvested and stained for CD4, CD44, PSGL-1, and CD62L. Gated CD4+CD44hi are shown as PSGL-1 versus CD62L. PSGL-1loCD62LloCD4+CD44hi cells were identified as extrafollicular PSGL1lo CD4+ T cells. Percentages of PSGL-1lo CD4+ T cells among CD4+CD44hi cells are shown as mean ± SE (n = 6). d CCR9 and FasL expression on splenic PSGL-11oCD4+ T cells were measured by flow cytometry and one representative histogram is shown (n = 6). Scale bar, 50 µm