Abatacept acts by:a. stimulating adenosine receptors.b. binding to MHC Class II on B cells.c. inhibiting B cell receptors.d. activating T cell receptors.e. binding CD80/86 on antigen-presenting cells

Which of the following is the primary activation signal to fully activate T helper cells?ANSWERThe TCR/MHC/antigen interaction is assisted by CD8 on the surface of T helper cells.The B7 protein on the APC cell surface interacts with CD28 on the surface of T helper cells.The TCR of the T helper cell interacts with the MHC I–antigen complex.The T-cell receptor (TCR) of the T helper cell interacts with the MHC II–antigen complex.

CD4 attaches to the base of MHC _______ and stabilizes the binding of antigen to the αβ receptors of ________ cells.1 pointI; TCI; THII; TCII; TH

Class I MHC molecule can ____________.bind to CD8 molecules on T cellspresent antigens to B cellsbind to CD4 molecules on T cellsbind to antibodies

T-cell activation begins when a/n presents an antigen fragment in association with an MHC-II molecule to a helper T cell. Once activated, helper T cells can differentiate into T helper 1 cells which will activate cells and secretes IL-2 to help activate cell-mediated immunity. CD4 helper T cells may also differentiate into T helper cells for B-cell activation, or T helper or T regulatory cells for modulation of the response. An APC may also activate a CD8 T cell when the antigen is complexed with . These CD8 cells are called T cells. Activated CD8 cells will mount a direct attack on target cells through the action of , which punch holes in membranes, and , which then enter through these passageways.

B cells, but not T cells, undergo affinity maturation. This may explain why only _______.1 pointT cells require co-receptors for stable bindingB cells produce a variety of classes of receptorT cells do not produce soluble versions of their receptorsB cells can present antigen on class I MHC