Macrophages eat cancer cells using their own calreticulin as a guide
Therapeutic and diagnostic methods are provided, which methods relate to the induction of expression of calreticulin on phagocytic cells. Specifically, the methods relate to macrophage-mediated programmed cell removal (PrCR), the methods comprising increasing PrCR by contacting a phagocytic cell with a toll-like receptor (TLR) agonist; or down-regulating PrCR by contacting a phagocytic cell with an inhibitor of Bruton's tyrosine kinase (BTK). In some embodiments, an activator of TLR signaling or a BTK agonist is provided in combination with CD47 blockade.
1. A method of increasing phagocytosis of cancer cells, the method comprising:
contacting a population of phagocytic cells in vitro with a TLR-3, TLR-4 or TLR-9 agonist in a dose effective to increase expression of calreticulin on the phagocytic cell surface; and with a CD47 blocking agent in a dose effective to increase phagocytosis of cancer cells;
introducing the population of phagocytic cells into a subject following the contacting with a TLR agonist and a CD47 blocking agent, wherein expression of calreticulin on the phagocytic cell surface is measured prior to the introducing step;
wherein programmed cell removal of cancer cells by the phagocytic cells is increased.
2. The method of claim 1 , wherein the CD47 blocking agent specifically binds CD47 to reduce the binding of CD47 to SIRPα.
3. The method of claim 2 , wherein the CD47 blocking agent is a high affinity SIRPα polypeptide.
4. The method of claim 2 , wherein the CD47 blocking agent is an anti-CD47 antibody.
5. The method of claim 1 , wherein the CD47 blocking agent specifically binds SIRPα to reduce the binding of CD47 to SIRPα.
6. The method of claim 5 , wherein the CD47 blocking agent is an anti-SIRPα antibody.
7. The method of claim 1 , wherein the TLR-3, TLR-4 or TLR-9 agonist is selected from LPS, BCG ( Bacillus of Calmette-Guerin), CpG ODN, Poly I:C, and Poly I:CLC.
8. A method of increasing phagocytosis of cancer cells in vivo, the method comprising:
contacting a population of phagocytic cells with a TLR-3, TLR-4 or TLR-9 agonist in vivo in a dose effective to increase expression of calreticulin on the phagocytic cell surface; and with a CD47 blocking agent in a dose effective to increase phagocytosis of cancer cells; and
monitoring expression of calreticulin on the phagocytic cell surface following the contacting;
wherein programmed cell removal of cancer cells by the phagocytic cells is increased.
9. The method of claim 8 , wherein the CD47 blocking agent is an anti-CD47 antibody.
10. The method of claim 8 , wherein the CD47 blocking agent is an anti-SIRPα antibody.
11. The method of claim 8 , wherein the TLR-3, TLR-4 or TLR-9 agonist is selected from LPS, BCG ( Bacillus of Calmette-Guerin), CpG ODN, Poly I:C, and Poly I:CLC.