Expression and properties of FR-β in peripheral blood granulocytes and in recombinant CHO–FR-β cells.

(A) FR-β expression detected in cell lysate by Western blot using anti–FR-β antibody. Band intensities were estimated using NIH Image software. (B) Differential sensitivity of FR-β GPI anchors to PI-PLC and nitrous acid; whole cells were treated with PI-PLC, and the cell lysates were analyzed by Western blot using anti–FR-β antibody. Alternatively, cell membranes were treated with nitrous acid and similarly analyzed. (C) Cellular binding of FITC-folate determined by flow cytometry. 10 nM FITC-folate was used with or without preincubation with 1 μM folic acid, as described in “Materials and methods.”