Final answer:
Cytokines are the small peptides released by various cells that influence the direction and intensity of an immune response. They are chemical messengers that regulate immune responses by affecting cell differentiation, proliferation, gene expression, and cell trafficking. Cytokines can trigger inflammation or other immune responses.
Step-by-step explanation:
The small peptides released by various cells that influence the direction and intensity of an immune response are known as cytokines. Cytokines are chemical messengers that regulate cell differentiation, proliferation, gene expression, and cell trafficking to affect immune responses. They can be released by injured, infected, or immune cells, and their release triggers inflammation or other immune responses.