Review the animation and answer the questions that follow to test your understanding.

1		On first exposure to antigen, T helper cells
			A)	become activated and increase in number
			B)	cause inflammation
			C)	cause skin lesions
			D)	attract more macrophages
2		When T helper cells are exposed for the second time to hapten-peptide on antigen presenting cells, they
			A)	lyse cells using perforin
			B)	release cytokines which attract more macrophages
			C)	make antibodies
			D)	kill macrophages
3		Skin lesions due to hypersensitivity appear
			A)	24 hours after first exposure to antigen
			B)	48–72 hours after first exposure to antigen
			C)	24 hours after second exposure to antigen
			D)	3 weeks after second exposure to antigen
4		A hapten is an antigen that is capable of causing antibody production on its own.
			A)	True
			B)	False
5		Delayed hypersensitivity is due to the effects of the humoral part of the immune system.
			A)	True
			B)	False