Question

The interaction of the MHC and the T cell receptor in T cell activation is called the first signal. Additional signals, known as costimulatory or second signals, are required for full T cell activation. What glycoprotein is one of the 2 best-characterized costimulatory molecules on antigen-presenting cells?

B7.1
VCAM-1
IL-8
LFA-1
IP-10

Answer 1

B7.1 is one of the well-characterized costimulatory molecules on antigen-presenting cells that works alongside another molecule, B7.2, to provide crucial secondary signals for complete T cell activation. Option A.

Step-by-step explanation:

The glycoprotein that constitutes one of the best-characterized costimulatory molecules on antigen-presenting cells (APCs) is B7.1.

This molecule, along with B7.2, is essential in providing the second signal required for T cell activation. Without this costimulatory signal, the T cell receptor's (TCR) recognition of an antigen presented with Major Histocompatibility Complex (MHC) - the first signal - would not suffice to fully activate the T cells.

Cytotoxic T cells and helper T cells both need this secondary confirmation to proceed with their immune response functions. This interaction is a crucial checkpoint to prevent unwanted T cell activation.

The B7.1 molecule mainly interacts with the CD28 receptor on T cells, providing the regulatory signal necessary for the T cell's effective response to a pathogen. So Option A.