The effect of ex vivo refrigerated storage and cell preservation solution (Cyto-Chex II™) on CD11b expression and oxidative burst activity of dog neutrophils

The expression of CD11b and oxidative burst activity of dog neutrophils undergoing ex vivo refrigerated storage was studied using flow-cytometry. Additionally, the effect of a proprietary cell stabilization reagent (Cyto-Chex(TM)) on the expression of CD11b and oxidative burst activity was studied. Expression of CD11b was very high (>90% positive) on dog neutrophils isolated from peripheral blood. Dog neutrophils showed a rapid and sustained increase in CD11b antigen density (P<0.01) during refrigerated storage, this increase was prevented by treatment with Cyto-Chex(TM) but was not completely blocked on the first day. There were no significant, differences in mean antigen density between any days in the non-preserved group or between Days 1 to 4 in the Cyto-Chex(TM) treated group. The non-treated group showed significantly greater mean antigen density at ail time points when compared to the preservative treated group (P<0.0001). Treatment with Cyto-Chex(TM) did not interfere with measurement of oxidative burst function on the first 2 days. Alterations of both resting oxidative activity and stimulated response were observed over time in both treated and untreated blood samples. Cyto-Chex(TM) treated samples showed a dramatic, significant decline in stimulated response after the third day of storage (P<0.001), while non-treated cells showed steadily increasing, but non-significant differences in stimulated response. Cyto-Chex(TM) was demonstrated to be a useful reagent for stabilization of dog neutrophil membrane antigens during storage, however this reagent is not recommended for preservation of cells for functional assays. (C) 2000 Elsevier Science B.V. All rights reserved.