| Summary: | Production of colony-stimulating factor (CSF) was examined in three patients with lung cancer associated with neutrophilia. All three patients presented a marked increase in neutrophil count (26,000-39,000 microliters-1) that continued at least for 3 weeks and rapidly disappeared after surgical removal of the tumours. Culture media (CM) incubated with the excised tumour tissues stimulated the colony formation of bone marrow myeloid progenitor cells in vitro. Northern blot analysis of poly(A)+ RNA from the tumour tissues revealed a constitutive expression of granulocyte (G), macrophage (M), and granulocyte-macrophage (GM) CSF genes in all tumours. Immunoassay specific for these CSFs revealed that G- and M-CSF immunoreactivity was detected in all CM and GM-CSF protein in two out of three CM. The plasma CSF levels also increased before operation and decreased to normal or near-normal range after operation. In contrast, tumour cell CM obtained from two lung cancer patients without leucocytosis neither stimulated haematopoietic colony formation nor contained immunoreactive CSFs. These results indicated that the neutrophilia found in the three patients was probably caused by constitutive production of multiple CSFs by lung cancer cells.
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