Figure Which of the following statements about T cells is false?
- Helper T cells release cytokines while cytotoxic T cells kill the infected cell.
- Helper T cells are CD4+, while cytotoxic T cells are CD8+.
- MHC II is a receptor found on most body cells, while MHC I is a receptor found on immune cells only.
- The T cell receptor is found on both CD4+ and CD8+ T cells.
Figure Based on what you know about MHC receptors, why do you think an organ transplanted from an incompatible donor to a recipient will be rejected?
Figure MHC receptors differ from person to person. Thus, MHC receptors on an incompatible donor are considered “non-self” and are rejected by the immune system.
Figure The Rh antigen is found on Rh-positive red blood cells. An Rh-negative female can usually carry an Rh-positive fetus to term without difficulty. However, if she has a second Rh-positive fetus, her body may launch an immune attack that causes hemolytic disease of the newborn. Why do you think hemolytic disease is only a problem during the second or subsequent pregnancies?
Figure If the blood of the mother and fetus mixes, memory cells that recognize the Rh antigen can form late in the first pregnancy. During subsequent pregnancies, these memory cells launch an immune attack on the fetal blood cells. Injection of anti-Rh antibody during the first pregnancy prevents the immune response from occurring.