CC chemokine receptor 5 (CCR5) is a member of the G-protein-coupled receptor superfamily. It plays an important role in macrophage tropic human immunodeficiency virus-1 entry and in some inflammatory reactions. CCR5-893(-) is a single-nucleotide deletion that results in complete truncation of the C tail of the gene product. We detected CCR5-893(-) in a sample of patients infected with non-tuberculosis mycobacteria and found that it was maintained heterozygously with a frequency of 2%. There is no association between this mutation and any immunodeficiency. Membrane expression of CCR5-893(-) was substantially reduced compared to the wild type, but this defective surface presentation recovered greatly recovered in the presence of 2 mg l(-1) phytohemagglutinin (PHA). However, PHA inducement did not affect the total intracellular expression of CCR5-893(-) or wild-type CCR5. Thus we suggest there exist some PHA-induced factor(s) that could mediate the presentation of truncated CCR5.