Towards understanding the immune system
  It is proposed that using both self-non-self and danger theories give a better understanding of how the immune system works. It is proposed that comparing immune system to police force is useful in this case since police responds both to danger or damage signals and to foreign or suspicious behavior even if no danger signals existed. We also propose that due to low zone tolerance immunotherapy needs to be combined with another treatment method for cancer e.g. chemotherapy or/and radiotherapy to get a sufficient eradication of tumors. Finally we propose that fractional order differential equations are more suitable than the familiar integer order differential equations. A fractional order example of two immune effectors attacking an antigen is given. 
E.Ahmed and A.H. Hashish