Vasoactive intestinal polypeptide as a biochemical marker for polymorphonuclear leukocytes.

VIP is a 28 amino acid peptide found in highest concentration in central and peripheral nervous tissue. This study measured VIP in pure populations of peripheral blood cells to determine the presence or absence of VIP in noninnervated tissues. Cell populations were purified by Ficoll-hypaque gradient centrifugation followed by dextran sedimentation or differential adherence to culture plates. Platelets were purified by differential centrifugation. VIP was isolated by acid-ethanol extraction and quantified by radioimmunoassay. A mean value of 1.1 +/- 0.6 ng of VIP per 10(8) cells was extracted from PMNs. This peptide appears to be a specific marker for PMNs, since it was not measurable in pure populations of lymphocytes, monocytes, erythrocytes, or platelets. Mononuclear cells obtained from five patients with AML and seven patients with CML contained measurable VIP, whereas mononuclear cells from nine of 10 patients with AMML and from five patients with ALL contained very low or unmeasurable levels of VIP. Thus, although the role of VIP in normal PMN function is unknown, measurement of VIP in leukemic cells may aid in the differential diagnosis of acute leukemias.