A distinct phenotype of blood neutrophils in CLL indicates aberrant migration during UTI. (A) Mice were induced with CLL, and the expression of CD62L and CXCR4 was determined on neutrophils by FC (gating shown in supplemental Figure 17). Dot plots indicate phenotypic alterations in protein surface expression on blood neutrophils of non-CLL (gray) and CLL-bearing mice (red). Control stainings are indicated as fluorescence minus one (FMO; black). (B-C) Mice were euthanized on day 42 post-CLL induction with a tumor burden (% CD5⁺ CD19⁺ in whole blood) >20%. The frequency of neutrophils for CD62L (B) and CXCR4 (C) was determined by FC. (D-E) Linear regression analysis of the indicated surface molecules on murine blood neutrophils. The CLL burden (% CD5⁺ CD19⁺ in whole blood) and frequencies of neutrophil subsets positive for CD62L (D) and CXCR4 (E) were determined by FC. (F) The expression of the surface molecules CD62L and CXCR4 was determined on blood neutrophils from patients with CLL (gating shown in supplemental Figure 17). Dot plots illustrate the phenotypic alterations in protein expression in patients with low CLL load (patient 2 with 34 830 lymphocytes per µL blood, gray) vs high CLL load (patient 5 with 166 939 lymphocytes per µL blood, red) analyzed by FC. Isotype control staining is also shown (black). (G-H) Linear regression analysis of CD62L (G) and CXCR4 (H) on blood neutrophils from patients with CLL (CLL burden = number of lymphocytes [×10⁴]/µL blood). (I) Incidence rate of respiratory infections (percentage of infections per year of monitored period) in correlation to CLL burden (number of lymphocytes [×10⁴]/µL blood) (detailed information of patient history is shown in supplemental Table 18). *P < .05. Data represent mean ± SEM. (A) Non-CLL, n = 5; CLL, n = 3. (F) Patients with CLL, n = 14. (A-E) Pregated on Ly6G⁺ neutrophils (shown in supplemental Figure 16). (F-H) Pregated on CD45^dim/high and CD16^−/+, CD45^high CD16⁻ eosinophils were excluded (shown in supplemental Figure 17).