Simplify the following text for a Grade 11 native English-speaking person.
Original: Medawar 's work resulted in a shift of emphasis in the science of immunology from one that attempts to deal with the fully developed immunity mechanism to one that attempts to alter the immunity mechanism itself , as in the attempt to suppress the body 's rejection of organ transplants .
Simplified: Medawar 's work resulted in a shift of emphasis in the science of immunology from one that attempts to deal with the fully developed immunity mechanism to one that attempts to alter the immunity mechanism itself . Various ways have been found to suppress the body 's rejection of organ transplants .