Recent advances in hantavirus molecular biology and disease.
intraalveolar cytokine production (19 ) or increased CD4 T lymphocytes in smokers (20 ). A suppressive effect of tobacco smoke on the human immune system has also been reported (21 ), which could explain the lower neopterin production of smokers in our study. We noted a correlation between neopterin concentrations and diastolic blood pressure values. Although an explanation for this correlation is not immediately evident, the possibility of a connection between immunoactivation and increased diastolic pressure cannot be excluded definitively. Recently, a correlation was reported between ischemic attack and both neopterin and the potent endothelial-derived, vasoconstrictive peptide endothelin-1 (22 ). Conditions such as atherosclerosis (16 ) or infections by Helicobacter pylori (23 ), which are associated with immune activation and higher neopterin production, might possibly lead to vasoconstriction and thereby increased diastolic blood pressure because of increased endothelin-1 production. The positive correlation that was found between neopterin concentrations and BMI, a correlation that was not an independent one, supports results of an earlier study in individuals with non-insulin-dependent diabetes mellitus (13 ), and it would be in line with earlier suggestions that long-lasting immune activation, even if only moderate, may contribute to the development of obesity (24 ). Nevertheless, our study of blood donors indicates that neopterin concentrations are associated with age, smoking status, diastolic blood pressure, and BMI, although the reasons for these associations are still unclear. The interindividual variation of neopterin concentrations among healthy individuals may, in part, be attributable to variations caused by these variables rather than analytical variation of the assay used.