Figure 4.

The immunological cascade in BCG treatment. Uptake of BCG by bladder urothelium triggers release of IL-6, IL-8, GM-CSF and tumor necrosis factors (TNFs) which recruit copious neutrophils to the bladder. These neutrophils chemoattract monocytes to the tumor environment through the release of CXCL1, IL-8, MIP-1, and MIF. It is thought that these monocytes subsequently induce T cell migration, possibly through the release of chemokines such as CXCL9 and 10. In the meantime, BCG activated dendritic cells migrate to the lymph nodes and prime antigen naïve T cells which then egress from the lymph node and are recruited to the tumor. Whilst γδ T cells are found in large numbers in the urine post BCG, it is unclear how they are recruited to the bladder.