PATHOLOGY

Detailed explanation-1: -helper T cell, also called CD4+ cell, T helper cell, or helper T lymphocyte, type of white blood cell that serves as a key mediator of immune function. Helper T cells play a central role in normal immune responses by producing factors that activate virtually all the other immune system cells.

Detailed explanation-2: -B cells can receive help from armed helper T cells when antigen bound by surface immunoglobulin is internalized and returned to the cell surface as peptides bound to MHC class II molecules. Armed helper T cells that recognize the peptide:MHC complex then deliver activating signals to the B cell.