Analysis of lymphoid cells and their subpopulations in the MLN. Cell suspensions isolated from MLN of control GF piglets and GF piglets infected with PRRSV, SIV or PCV2 (different animal groups depicted on x-axes) were analyzed by flow cytometry for the proportion of B cells (A) and some of their subpopulations (D-F), αβ T cells (B) and their subpopulations (G-I) and γδ T cells (C) and their subpopulations (J-L). The phenotype of individual cell subpopulations is depicted above each graph. Note that the proportion of NK cells and CD2—CD21— B cell subpopulation did not differ between experimental groups and therefore these are not shown. Each dot in the graphs represents an individual animal and the mean for all animals in the same group is indicated by a horizontal line. Groups of animals that show a statistically significant difference (p < 0.05) from GF animals are light-grey boxed and those differing even within a group are dark-grey boxed.