Multiple Choice
Cytotoxic T cells are responsible for which of the following responses?
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21. The Immune System
T Cells
Multiple Choice
In adaptive immunity, what event most directly initiates activation of a naïve T cell?
A
Binding of soluble antigen directly to the T-cell receptor without antigen presentation
B
Complement activation leading to membrane attack complex formation on the T-cell membrane
C
Engagement of the T-cell receptor (TCR) with a specific peptide presented on MHC molecules of an antigen-presenting cell, along with required co-stimulatory signaling (e.g., CD28 binding B7)
D
Recognition of pathogen-associated molecular patterns by Toll-like receptors on the T cell alone
Verified step by step guidance1
Understand that naïve T cell activation requires specific antigen recognition, which is not achieved by soluble antigen binding directly to the T-cell receptor (TCR) without presentation.
Recognize that complement activation and membrane attack complex formation are part of innate immunity and do not directly activate T cells.
Recall that T cells recognize antigens only when peptides are presented on Major Histocompatibility Complex (MHC) molecules by antigen-presenting cells (APCs).
Identify that the critical event is the engagement of the TCR with the peptide-MHC complex on the APC surface, which provides the first activation signal.
Remember that a second, co-stimulatory signal (such as CD28 on the T cell binding to B7 on the APC) is also necessary to fully activate the naïve T cell and prevent anergy.
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