Figure 1. Characterization and longitudinal analysis of MDSC populations in cord blood, infants and adults.

(A) Gating strategy and identification of HLA-DR/CD14^neg, CD33/CD11b/CD15^pos G-MDSC in adult and cord blood. Further characterization of HLA-DR/CD14^neg, CD33/CD11b/CD15^pos cells by intracellular staining of Arginase I. (B) Frequency of HLA-DR/CD14^neg, CD33/CD11b/CD15^pos cells of: (i) CBMC isolated from CB collected from healthy pregnancies in Seattle, WA (n = 25); (ii) PBMC isolated from neonates in Cape Town, South Africa at 6-weeks of age (n = 9); (iii) PBMC isolated from 6–24 month-old infants in Seattle, WA (n = 29); (iv) and PBMC isolated from healthy adults in Seattle, WA (n = 28). Statistical significance determined by the Mann Whitney test. (C) Wright-Giemsa cytospin of CB samples and phenotype determination by clinical pathology of neutrophils and G-MDSC (Average, n = 2 independent experiments). Magnification 600X. (D) Proportions of neutrophils at various stages of development in the neutrophil and the G-MDSC fractions.