The term “tolerance” refers to responses observed which include long-term graft acceptance without the need for chronic immunosuppression. There are a variety of specific ways in which T and B lymphocytes can be tolerant or nonresponsive to antigen. Which of the following is/are mechanisms of tolerance?
A.	Clonal abortion
B.	Clonal deletion
C.	Clonal anergy
D.	Suppression
Answer:A
The term “tolerance” refers to responses observed which include long-term graft acceptance without the need for chronic immunosuppression. There are a variety of specific ways in which T and B lymphocytes can be tolerant or nonresponsive to antigen. Which of the following is/are mechanisms of tolerance?
A.	Clonal abortion B.	Clonal deletion C.	Clonal anergy D.	Suppression