19. CD4 and CD8 are
(A) proteins secreted by antigen-presenting cells
(B) receptors present on the surface of natural killer cells
(C) T-independent antigens
(D) molecules present on the surface of T cells where they interact with major histocompatibility (MHC) molecules

(E) molecules on the surface of antigen-presenting cells where they enhance B-cell activity

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統計: A(0), B(0), C(1), D(1), E(0) #3828134