ABSTRACT
According to the growth or nitrogen (N) balance of animals, amino acids (AA) have been traditionally classified as nutritionally essential AA (EAA) or nutritionally nonessential AA (NEAA). Arginine has long been considered an NEAA for adult animals including humans, but has recently been classified as a nutritionally semi-essential AA for young mammals, as well as males and females of reproductive age. This chapter describes the effects of arginine on immune function and the mechanisms involved. The humoral and cell-mediated immune responses orchestrate adaptive immunity in the host. Humoral immunity is the responsibility of B lymphocytes, which produce antibodies targeted to specific antigens, while cell-mediated immunity is associated with T lymphocytes, which activate other immune cells and kill infected cells. Regulatory T-cells are important immunoregulators in many inflammatory and autoimmune diseases as they modulate secretion of anti-inflammatory cytokines and the expression of receptors for cytokines.
