Genotype-dependent development of cellular and humoral immunity in spleen and cecal tonsils of chickens stimulated in ovo with bioactive compounds

Abstract Bioactive compounds, such as prebiotics probiotics and synbiotics delivered in ovo influence the colonization and development of the peripheral immune system in poultry. This study aimed to investigate the influence of the host genotype on the number of B and T cells in spleen and cecal tonsil in chicken. Two distinct chicken genotypes were used: broiler chicken (Ross 308) and old native Polish breed Green-legged Partridgelike (GP). The solution of a bioactive compound was injected in ovo into the air cell on day 12 of egg incubation. The bioactive compounds were: prebiotic (GOS, galactooligosaccharides), probiotic (Lactococcus lactis subsp. cremoris IBB477) and synbiotic (GOS + L. lactis). Control eggs were mock-injected with physiological saline (C). The samples of spleen and cecal tonsils (CT) were collected on days: d7, d21, and d42 after hatching (n=8). The number of Bu-1+ (B) cells, CD4+ cells and CD8+ cells in spleen and CT were estimated using immunohistochemistry. The number of germinal centers (GC) was determined in spleen. In broilers, probiotic increased (P