Clinical significance of monocytosis and human monocytic colony-stimulating factor in patients with adult T-cell leukaemia/lymphoma.

We studied 79 patients with adult T-cell leukaemia/lymphoma (ATL) and 11 human T-lymphotropic virus-type I (HTLV-I-carriers to investigate the clinical significance of absolute monocyte counts in peripheral blood. Monocytosis was observed in 20% of ATL patients, but in none of the HTLV-I carriers. ATL patients with absolute monocyte counts above 1.5 x 10(9)/l had a poorer prognosis than those with counts less than 1.5 x 10(9)/l. We also investigated serum levels of human monocytic colony-stimulating factor (hM-CSF) in 7 ATL patients and 11 HTLV-I carriers at the time of diagnosis before chemotherapy, and also in 5 normal healthy individuals. The differences among the 3 groups were not statistically significant. However, markedly increased serum hM-CSF levels were found in 3 ATL patients who were considered to be in the accelerated phase of the disease and 2 of whom were previously diagnosed and had received chemotherapy. There was no correlation between serum hM-CSF level and absolute monocyte count in ATL patients or HTLV-I carriers. The results of hM-CSF assay of supernatants of cultured ATL cells revealed that the ATL cells did not produce hM-CSF themselves. In an ATL patient with pleural involvement, the pleural hM-CSF level was lower than the serum level. These facts indicate that absolute monocyte count is one of the prognostic factors in ATL and the source of the elevated hM-CSF level in some patients with ATL is not ATL cells.(ABSTRACT TRUNCATED AT 250 WORDS)