Abstract
The pterins neopterin and xanthopterin have been measured together with the cytokines IFN-γ, TNF-α and TNF-β in the supernatants of 20 allogeneic mixed lymphocyte reactions. We have calculated rank correlation coefficients between these analytes and the immune response. Our findings confirm that neopterin is a sensitive early marker of immune activation and show that another pterin, xanthopterin could be used likewise. Cytokine production was also proportional to immune activation but none could be used consistently as early markers of immune activation.