Regression plots for the number of adhered sickle erythrocytes (SS RBC)/100 μm2 relative to venular diameters in ex vivo preparations treated as follows: (A) PAF alone, (B) PAF and peptide FWV, (C) PAF and peptide ATSR and (D) PAF and control peptide AWSS. The regression lines represent the multiplicative equation of the form Y = aX-b for the best fit. In preparations treated with PAF alone, adhesion of sickle erythrocytes showed a strong correlation with the venular diameter. Preparations treated with peptide FWV or ATSR showed a marked inhibition of sickle erythrocyte adhesion in venules of all diameters, with ATSR having the maximal inhibitory effect, especially in small-diameter venules, the sites of frequent blockage. In contrast, in the presence of the control peptide AWSS, the resulting adhesion was essentially similar to that observed in PAF-treated preparations. Modified from Kaul et al. (50).