CYTOTOXIC ACTION OF POLYMORPHONUCLEAR LEUKOCYTES ON TUMOR AND NORMAL CELLS DURING ASCITE TUMOR DEVELOPMENT IN VITRO
AND IN VIVO
M. M. Potselueva, A. V. Pustovidko, E. V. Kovaleva, Yu. V. Shatalin, Yu. V. Evtodienko
Institute of Theoretical and Experimental Biophysics RAS, Puschino, Moscow Region, Russia
e-mail: potselueva@iteb.ru
A vast number of studies, including the authors' own research, support the important role polymorphonuclear
leukocytes (PMNL) in the development of ascite tumors. The method of luminol-dependent chemilummescence (CL) was used to show the
presence of two functionally different PMNL pools in a tumor-bearing organism: 1) "primed" PMNL, which circulate in the blood stream,
and 2) "activated" PMNL, which are accumulated in the tumor zone and are capable of spontaneous CL. The purpose of the present
investigation was to compare cytotoxic effects of primed and activated PMNL on tumor cells (ascite Ehrlich carcinoma (AEC), ascite
Zajdel hepatoma) upon co-cultivation, as well as on normal cells of the organism, erythrocytes in vitro and in vivo. Upon stimulation
with phorbol myristate acetate (PMA), PMNL effectively damaged AEC cells within the first 24 h until PMNL apoptosis occurred. Upon
further co-cultivation, the tumor cells grew in number, which suggest the participation of PMNL in tumor protection. When stimulated
with PMNL, pools suppressed tumor growth in vitro, since in this case the cytotoxicity was due to both reactive oxygen species
and proteolytic enzymes. As it has been shown earlier by the authors, the functional potential of PMNL increases many times during
tumor growth, and we suggested that not only tumor but also normal cells could be damaged. In this connection, we have studied the
cytotoxic effect of primed and activated PMNL on rat erythrocytes in vitro on their co-cultivation. On stimulation with PMA, the rate
of lysis of erythrocytes by primed PMNL increase many times compared to the norm. The fMLP-stimulated cytotoxity was 1.5-2.0 times
higher than in the norm. Activated PMNL without stimulation are capable of producing only a partial lysis of erythrocytes (5-7 %).
In order to assess the cytotoxic action of PMNL on erythrocytes in vivo, the hemoglobin content in erythrocytes and blood
plasm of rats was measured in the course of tumor growth. The hemoglobin content in erythocytes during growth tumor decreased from
135 ± 10 to 85 ± 5 g/1, whereas in the blood plasm the hemoglobin content gradually increased by almost two times. The results
enable us to suggest that one of death causes of tumor-bearing organisms may be the cytotoxic action of PMNL on normal cells of
the organism caused by hyperproduction of ROS.
Key words: polymorphonuclear leukocytes, ascite tumors, chemiluminescence method, priming, cytotoxicity
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