Decreased deformability of polymorphonuclear leukocytes in diabetic cats

Polymorphonuclear leukocytes (PMN) have been found to be less deformable in humans with non-insulin-dependent diabetes. It has therefore been hypothesized that white blood cells (WBC) may affect the development of diabetic microangiopathy. This study was designed to determine whether PMN or small and large lymphocytes were less deformable in a large animal model of diabetes-chronically hyperglycemic pancreatectomized cats.

Venous blood was withdrawn from 13 normal and 14 diabetic cats. The diabetic cats had been kept in poor metabolic control since their pancreatectomy (7-113 months before this study). Blood cell counts, hemoglobin concentration, hematocrit, erythrocyte volume, and WBC differential counts were obtained from the blood samples. Purified mononuclear WBC and PMN fractions were obtained by separating the blood on a discontinuous Percoll gradient. The deformability of each cell fraction was determined using a Cell Transit Analyzer (ABX, Montpellier, France) that measures the transit time of cells through 7.5-microns pores. By varying the sampling rate of the CTA and the pressure difference across the filter, the subpopulations of the mononuclear fractions (small and large lymphocytes) could be identified and each subpopulation analyzed separately.

Median transit times for the PMN and small lymphocytes were significantly greater for the diabetic cats, but no difference was found in the large lymphocyte fractions.

These results are in accordance with the finding that PMN are less deformable in humans with diabetes. We also showed that the small lymphocytes from diabetic cats have prolonged transit times. The results suggest that PMN may contribute to the development of microangiopathies like diabetic retinopathy. Diabetic cats may prove useful for testing potential therapies to improve WBC deformability.