CORTICOTROPIN-RELEASING FACTOR AND ACTH-RELATED FRAGMENTS MODULATE THE PHAGOCYTIC-ACTIVITY OF HUMAN MONOCYTES

The effect of CRF and some ACTH fragments on the bacterial phagocytic activity of human monocytes was studied. The findings show that an immunomodulating effect on the phagocytosis of Staphylococcus aureus is exerted not only by a relatively large fragment, such as ACTH(1-24), but also by a small four aminoacid fragment, such as ACTH-(1-4), Indeed, a significant increase of phagocytic index (ratio between the mean number of bacteria phagocytized in the presence and in the absence of the peptides) was observed with 10(-8)M ACTH-(1-24) and 10(-11) M ACTH-(1-24) and ACTH-(1-4). The data indicate a possible important function of ACTH in human pathophysiology, and suggest that these molecules may play a role in the cross-talk between the immune and neuroendocrine systems.