Leukocyte concentration
A 20μl blood filled capillary was released in 1ml of a kit solution (LEUKO-TIC “blue”, Bioanalytic, Germany). This solution allows a microscopic count of leukocytes after the lysis of the erythrocytes and the fixation of the leukocyte nucleus colored in light blue. The leukocyte counts were done at x100 enlargement using a Malassez counting chamber by a single observer (C.R.). Only the leukocytes entirely located inside the four 1mm² corner squares (total volume of 4*1mm2*0.2mm = 0.8µl) were counted. All the leukocyte counts were done within 24 hours after blood collection.
Between 2013 and 2015, the leukocyte concentration was determined for 79 samples from 34 dominant individuals sampled between two and three times. 23 individuals had two samples in different years and 11 individuals had three.
Leukocyte counts
Immediately upon blood collection, a drop of blood was smeared onto a slide, later stained with Giemsa stains using an aerospray (Aerospray Hematology Slide/Cytocentrifuge 7150, Wescor, France). Neutrophils, lymphocytes, monocytes, eosinophils and basophils were counted (observer: CR) up to 100 leukocytes, at 100x enlargement, according to Hawkey and Dennett’s criteria (Hawkey & Dennett, 1989). The basophil count was low for nearly all individuals (min = 0, max = 49, median = 0) and therefore excluded in the subsequent analyses.
Between 2011 and 2015, the leukocyte counts were determined for 169 blood smears from 52 dominant individuals sampled between two and five times. 18 individuals had two samples in different years, 12 had three, 13 had four, and 9 individuals had five. 33 of them were both measured for leukocyte concentration and leukocyte counts (which corresponds to 75 measurements).