[A low molecular weight fraction of human leukocyte dialysates with potential immunostimulatory activity. IMREG-1 is shown to augment and accelerate human delayed type hypersensitivity (DTH) to recall antigen in vivo, potentiate production of interleukin-2 (IL-2) and interferon gamma, and induce expression of IL-2 receptor in peripheral blood mononuclear cells,. These effects are attributed to the peptides Tyr-Gly and Tyr-Gly-Gly, which are identical to the N-terminal end of the enkephalins. Studies in HIV patients have shown that this agent may delay progression to more serious disease and improves laboratory markers. ( NCI )] (UMLS (NCI) C0063442) =Amino Acid, Peptide, or Protein; Pharmacologic Substance