Final answer:
B cells, or B lymphocytes, are unique to the humoral immune response and are responsible for producing antibodies that combat pathogens in body fluids.
Step-by-step explanation:
The cells that are unique to the humoral immune response are B cells (B lymphocytes). B cells are responsible for producing antibodies that circulate in the body's fluids or humors, hence the term 'humoral'. This type of immunity is distinct from the cell-mediated immunity, which involves T cells. T cells are crucial for attacking infected cells, but do not produce antibodies. It is the activated B cells, also known as plasma cells, that produce antibodies specific to antigens that the immune system has recognized.