Fig. 6

Infant intestinal NK cells contain high levels of cytotoxic granules. a viSNE plots of combined flow cytometric data visualizing Eomes, perforin, granzyme B, and KIR expression by epithelial (EP) and lamina propria-derived (LP) infant and adult NK cells. Expression of Eomes, KIR, perforin, and granzyme B (GrzB) is shown by color coding in relative intensity. viSNE plots have been calculated from concatenated FCS files gated on NK cells (infant samples N = 7, adult samples N = 5, iterations = 7500 perplexity = 100, KL divergence = 2.62). b Frequencies of perforin⁺ and GrzB⁺ NK cells in infants (white circles) and adults (dark circles) (EP infant samples (N = 8), LP infant samples (N = 7), EP adult samples perforin expression (N = 9), GrzB expression (N = 8), LP adult samples perforin expression (N = 9), and GrzB expression (N = 8)). c Frequencies of perforin⁺ and granzyme B⁺ cells within CD103⁺, CD49a⁺, or CD69⁺ NK cell populations in infant (white circles) and adult intestines (dark circles) (EP infant samples (N = 8), LP infant samples (N = 7), EP adult samples perforin expression (N = 9), and GrzB expression (N = 8), LP adult samples perforin expression (N = 9), and GrzB expression (N = 8)). d Frequencies of LP-derived CD107a⁺, IFN-ɣ⁺, and TNF-α⁺ NK cells in infant (white circles) and adult intestines (dark circles). Cells were stimulated for 6 h with phorbol 12-myristate 13-acetate (PMA) and ionomycin (infant samples N = 5, adult samples N = 7). e Frequencies of LP-derived CD107a⁺ cells within CD103⁺, CD49a⁺, or CD69⁺ NK cell populations in infant (white circles) and adult intestines (dark circles) after stimulation with PMA and ionomycin for 6 h (infant samples N = 5, adult samples N = 6). Median frequencies indicated by red lines. Error bars define interquartile ranges between 75th and 25th percentiles. Statistical comparisons are Mann-Whitney U comparisons (b, d) and Wilcoxon matched-pairs signed rank tests (c, e). Asterisks represent the following p-values: *p < 0.05; **p < 0.01; and ***p < 0.001