Final answer:
B cells, macrophages, and dendritic cells serve as antigen-presenting cells (APCs) that present antigen fragments in association with MHC molecules to T cells, leading to the production of cytokines and mobilization of the adaptive immune response.
Step-by-step explanation:
B cells, along with macrophages and dendritic cells, serve as antigen-presenting cells (APCs) that present to T cells in response to intracellular pathogens. The cytokines produced depend on the types of T cells activated. For instance, helper T cells produce cytokines that can recruit more immune cells or activate other T cells, while cytotoxic T cells directly kill infected cells.
When an intracellular pathogen infects APCs, antigens are presented on the cell surface in association with MHC molecules, specifically MHC I for CD8 T cells or MHC II for helper T cells. In some cases, dendritic cells can also utilize cross-presentation to present antigens from extracellular pathogens on MHC I molecules. B cells, although not primary phagocytes, can internalize antigens through their immunoglobulin receptors (IgD and IgM) and then present the antigens to T cells post-processing. These interactions of APCs with T cells are crucial for the appropriate mobilization of the adaptive immune response against intracellular pathogens.