Figure 1. Heterologous lymphocyte responses includes: A. Molecular mimicry between the BCG vaccine and antigens of unrelated pathogens, can cause a cross-reactive immune response to these unrelated antigens (blue coloured antibodies attacking red coloured cells, in the antigen cross-reactivity panel) B. Polyclonal activation of bystander B-/T-cells by BCG vaccination (red coloured antibodies attacking red coloured cells in the bystander lymphocyte activation panel) or C. non-specific lymphocytic response can trigger activation of innate immune cells like macrophages (grey coloured amoeba shaped cells), which secrete cytokines active against unrelated pathogens.
