Up-regulation of intracellular and cell surface CXCR4, functionally expressed by R4⁻ sorted cells.

CXCR4 expression by R4⁻ cells was determined following cell sorting and after in vitro cultures. (A) Intracellular CXCR4 expression. (Ai) Time 0. (a) Isotype control antibody, (b) R4⁻ sorted cells time 0, (c) nonsorted total CD34⁺ cells. (Aii) Up-regulation following 24 hours with 5 cytokines. (b) R4⁻ sorted cells time 0, (d) R4⁻ cells cultured for 24 hours with 5 cytokines. (B) Cell surface staining. (Bi) Time 0. (Bii) Migrating cells following 2 hours of sorting plus 4 hours in transwells. (Biii) 24 hours with 5 cytokines. (Biv) 24 hours with 5 cytokines plus a high concentration of SDF-1, 1μg/mL. (Bv) 24 hours without cytokines. Cell viability was 56%. (Bvi) 48 hours with 5 cytokines. (C) In vitro migration. sm indicates spontaneous migration—without SDF-1 at the lower chamber; cm, migration of sorted cells toward SDF-1. Culture conditions: 5 cyt indicates 5-cytokine combination. SDF-1 des indicates 1μg/mL SDF-1. A-B, representative FACS analyses. Data summarize 3 experiments.