Natural resistance-associated macrophage protein gene (Nramp) was isolated from the gene locus Lsh/Ity/Bcg, which regulates macrophage activation for antimicrobial activity against intracellular pathogens. The deduced protein sequence encodes an integral membrane protein that has structural homology with known prokaryotic and eukaryotic transport systems. In the present study, a polyclonal antibody was raised with the synthetic peptide of the carboxy-terminal 17 amino acids of human Nramp. The protein product of the gene is apparently present in human peripheral blood lymphocyte (PBL) as a 60 kD a protein recognized by the antibody, which is consistent with the calculated molecular mass. Bacterial lipopolysaccharide or interferon-gamma did not appear to stimulate the level of Nramp expression in PBL.