Lymphocyte subsets in peripheral blood of dogs - a flow cytometric study

Slight differences in the results of papers describing lymphocyte subsets d istribution in the peripheral blood of healthy dogs may be explained by dif ferences in monoclonal antibody clones and sources, breed and age of animal s examined, methods of sample treatment, or methods of result analysis. In this paper, we described the effect of sample processing and of sample stor age as well as the effect of age, breed, and gender of dogs on lymphocyte s ubset distribution. No significant differences were, found between samples processed following a whole-blood lysis method and samples processed after density gradient separation. Furthermore, no significant differences were f ound between samples processed within 2 h after collection and those stored at 4 degreesC for 12-16 h before processing. Age-related changes were evid ent in lymphocyte subset distribution in the peripheral blood of 38 Beagles divided according to their age into the six groups: (1) 5-6 days; (2) 2 mo nths; (3) 6 months; (4) 1-2 years; (5) 3-5 years; and (6) >5 years. ne perc entage of B-lymphocytes (CD21-like positive cells) in the peripheral blood of newborn pups was 39.5 +/- 5.7 and decreased with advancing age. The perc entage of CD8+ lymphocytes was 7.7 +/- 3.4 after birth and increased with a dvancing age. No age-related changes were observed in the percentages of CD 4+-lymphocytes. The CD4+:CD8+ ratio decreased with advancing age. No signif icant age-related change was observed for lymphocytes bearing the gamma del ta -TCR. Some breed differences were evident. Adult (1-5-year-old) Beagles, German Shepherds, Dalmatians, and Dachshunds were examined. The percentage s of lymphocytes were higher in Beagles and Dachshunds than in Dalmatians a nd German Shepherds. The highest and the lowest absolute lymphocyte counts were found in Beagles and German Shepherds, respectively. As a consequence, German Shepherds showed the lowest absolute counts of the individual lymph ocyte subpopulations and the widest neutrophil: lymphocyte ratio. Dalmatian s showed the lowest percentage of CD3+ cells, the highest percentage of CD2 1+ cells, and the lowest CD4+:CD8+ ratio. German Shepherds showed the lowes t percentage of CD21+ cells and the highest CD4+:CD8+ ratio. Females in Bea gles and Dachshuns had nonsignificantly higher percentages of total lymphoc ytes, CD3+, CD4+, and nonsignificantly lower percentages of CD21+ lymphocyt es. We concluded that there are age-, breed-, and perhaps also gender-relat ed differences in lymphocyte subset distribution in the peripheral blood of dogs. Therefore, there is need to use appropriate control group in the exp erimental protocols. Among-breed differences could explain, at least partly , breed predisposition for some diseases. (C) 2001 Elsevier Science B.V. Al l rights reserved.