Briefly describe how T cells and B Cells respond to pathogens

Helper T-cells stimulate B-cells to make antibodies and help killer cells develop. Killer T-cells directly kill cells that have already been infected by a foreign invader. T-cells also use cytokines as messenger molecules to send chemical instructions to the rest of the immune system to ramp up its response.

B cells produce antibodies, which bind to antigens and either block viruses and bacteria from entering cells (neutralizing antibodies) or trigger additional immune defenses. The two main types of T cells are CD4 and CD8 cells. CD4, or helper, T cells coordinate the immune response. These are the primary targets of HIV.

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