Characterization of purified CB-derived Lin⁻CD34⁻ cells.

(A) The forward scatter/side scatter (FSC/SSC) profile of immunomagnetically separated cells. The R1 gate was set on the lymphocyte window. (B) Cell-surface expression of 13 lineage markers, including CD2, CD3, CD4, CD7, CD10, CD14, CD16, CD19, CD20, CD24, CD41, CD56, and GPA on cells residing in the R1 gate. Cells residing in the R2 gate were further subdivided into 3 fractions according to their expression levels of CD34 antigen. (C) Isotype control. (D) Cells residing in the R3, R4, and R5 gates were classified as Lin⁻CD34^high, Lin⁻CD34^low, and Lin⁻CD34⁻ cells, respectively. The definitions of CD34^high, CD34^low, and CD34⁻ fractions are as follows: the CD34^highfraction contains cells expressing maximum phycoerythrin (PE) fluorescent intensity (FI) to 15% level of FI; the CD34^lowfraction contains cells expressing 5% to 1% level of FI; and the CD34⁻ fraction contains cells expressing less than 0.5% level of FI, respectively. (E-G) The expression patterns of CD34 antigen on CD45⁺ cells derived from the 7-day cocultures of CD34^high (E), CD34^low (F), and CD34⁻ (G) cells with the murine stromal cell HESS-5 in the presence of a cocktail of cytokines.