Cell-surface binding of HRF/TCTP to purified human basophils. Purified human basophils were incubated with HRF/TCTP and then with an anti-HRF antibody. Flow cytometry was performed as described in “Methods.” (A) Shift in MFI (dark histogram) is compared with an IgG control antibody (gray histogram) in an HRF/TCTP-R donor. (B) Shift in the MFI in an HRF/TCTP-NR donor. Panels A and B are representative of a total of 4 HRF/TCTP-R and 4 HRF/TCTP-NR donors, respectively. The left-hand side of the figure depicts the percentage increase in MFI in 4 HRF/TCTP-R donors (●) compared with 4 HRF/TCTP-NR donors (□) when stimulated with increasing doses of HRF/TCTP. There is a statistical difference between the 2 types of donors only at the 0.65-μM dose of HRF/TCTP with a P value of .036. The standard error is represented by the error bars.