2) Role of Th cells in humoral immune response to TD-Ag For a protein Ag to stimulate Ab response, b cells and th cells specific for that Ag must come together in lymphoid organs and interact in a way that stimulates B cell proliferation and differentiation2) Role of Th cells in humoral immune response to TD-Ag  For a protein Ag to stimulate Ab response, B cells and Th cells specific for that Ag must come together in lymphoid organs and interact in a way that stimulates B cell proliferation and differentiation