IS IMPAIRED RED-CELL FILTRATION IN DIABETICS DUE TO A SMALL ABNORMAL SUBPOPULATION OF CELLS

Differences in filtration between RBC's from diabetics and normal subj ects were readily detected with nickel filters but not using polycarbo nate filters. Parallel measurements using the CTTA demonstrated that a lthough the mean transit time of diabetic and normal cells was similar the more rigid cells within the samples from diabetics were significa ntly less deformable. This suggests that the abnormalities detected by nickel filters were due to a sub-population of less deformable cells rather than an abnormality of diabetic cells as a whole. In a further study where increasing numbers of glutaraldehyde hardened cells were a dded to normal red cell samples the CTTA instrument showed that 10% of hardened cells could be detected without any change being shown in th e mean transit time. At this level the nickel filter was much more sen sitive than the Nucleopore filter at detecting the subpopulation of ha rdened cells. Taken together these data support the hypothesis that di abetics have a small circulating sub-population of rigid red cells tha t can be readily detected using nickel filters.