Immunologically Privileged Sites

Immunological responsiveness to interleukin-2-producing brain tumors can be restored by concurrent subcutaneous transplantation of the same tumors

“…18 -22 The CNS, however, is considered to be an immunologically privileged site where a systemic immune response fails to prevent tumor growth. [3][4][5][6][7] Sampson et al 11 reported that s.c. vaccination with irradiated, cytokine-producing tumor cells was effective for the treatment of brain tumors, but complete elimination of brain tumors was seldom achieved by this strategy. We have shown that s.c. inoculation of 9L/IL-2 cells suppressed the growth of i.c.…”

“…1,2 The central nervous system (CNS) has been demonstrated to be tolerant to immunological responses, and consequently is considered to be an "immunologically privileged" site. 3,4 Impaired immunological reactions in the brain were also evidenced by other studies in experimental and clinical immunotherapies for brain tumors. [5][6][7] Recent studies, however, showed that cytokines such as interleukin-2 (IL-2), IL-4, or granulocyte-macrophage colony-stimulating factor secreted from tumor cells could suppress the growth of inoculated brain tumors, although complete elimination of the tumors was rarely observed.…”

Genetically engineered Sertoli cells are able to survive allogeneic transplantation

“…[1][2][3][4] This immunoprotective environment is due in part to the secretion of immunosuppressive molecules by Sertoli cells (SCs) [5][6][7] that allow ectopically transplanted SCs to survive as allografts [8][9][10] and concordant (rat-to-mouse) 11 and discordant (pig-to-rat) 12,13 xenografts in rodents. In addition to the ability of transplanted SCs to protect themselves in immunologically foreign environments, SCs were shown to protect islets and neuronal cells from immunemediated rejection.…”

Down-regulation of MHC class I expression in human neuronal stem cells using viral stealth mechanism

“…Due to their multipotency, NSCs can be applied for curing neuronal injuries and neurodegenerative diseases. The CNS has historically been considered to be an immune privileged site due to the low level of MHC expression in a normal brain, a relative lack of antigen presenting cells, and reduced lymphatic drainage [7][8][9][10][11][12][13][14]. However, the immune privilege of the CNS is not absolute and active transplant rejection can occur at a high frequency between genetically different individuals [15][16][17][18].…”