ACTH-like molecules in lymphocytes. A study in different vertebrate classes.

Immunocytochemical and cytofluorimetric studies were performed in several species of different classes (Pisces, Amphibia, Reptilia and Aves), in order to ascertain the presence of ACTH-like molecules in blood cells. Using monoclonal and polyclonal antibodies, we demonstrated that lymphocytes containing ACTH-like molecules are first detectable in anuran amphibia, and are present in lymphocytes of reptilia and aves. Taking into account previous results demonstrating that ACTH-like molecules are present in and modulate macrophage functions from molluscs to man, it is argued that a new biological role has probably been acquired by ACTH in higher vertebrates, where it is also expressed in cells belonging to the lymphocyte lineage, possibly exerting a regulatory role on antibody response.