FIG. 5.

TSA-1 is not an obligate requirement for T- or B-lymphoid differentiation. (A) Fetal thymic organ culture of E14 thymic lobes from wild-type (TSA-1^+/+) and TSA-1-deficient (TSA-1^−/−) embryos. Cells were harvested after culturing thymic lobes for 7 days and were analyzed for αβTCR expression (upper panels) and CD4 and CD8 surface marker expression (lower panels) by flow cytometry. (B and C) Lymphoid reconstitution of RAG-1^−/− mice with wild-type (TSA-1^+/+), heterozygous (TSA-1^+/−), and homozygous (TSA-1^−/−) hematopoietic precursors from fetal liver. PBLs were harvested from reconstituted animals 7 weeks after engraftment with fetal liver cells. Flow cytometry analysis was carried out using B220 and αβTCR specific MAbs to label B cells and T cells, respectively (B). Numbers shown indicate the percentage of B and T cells present in reconstituted animals. Donor cell TSA-1 genotypes were verified by immunostaining with the TSA-1 specific MAb GR12 (C).