Antigen recognition by CD4-positive T cells requires:

Question

Quizplus · Accepted Answer

CD4-positive T cells are helper T cells, which recognize antigen only when it is displayed on the surface of an antigen-presenting cell (APC) bound to class II major histocompatibility complex (MHC) molecules. Class I MHC molecules present antigen to CD8-positive T cells, while class III MHC molecules encode complement proteins and other molecules involved in immune responses. Therefore, the correct answer is B, as antigen recognition by CD4-positive T cells requires class II MHC molecules. Choice A is incorrect because CD4-positive T cells do not recognize antigens presented on class I MHC molecules. Choice C is incorrect because class III MHC molecules are not involved in antigen presentation. Choice D is incorrect because CD4-positive T cells require MHC molecules for antigen recognition.

Antigen Recognition by CD4-Positive T Cells Requires