Analysis of lymphoid cells and their subpopulations in the BAL. Cell suspensions isolated from the BAL 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 their subpopulations (E-H), αβ T cells (B) and their subpopulations (I-K), γδ T cells (C) and their subpopulations (L-N) and NK cells (D). The proportion of cells in lymphoid regions is also shown (O). The phenotype of individual cell populations is depicted above each graph. 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.