HDLM-2

Effect of ECP on Hodgkin Lymphoma Cell Lines

In HL, tumor eosinophilia indicates poor prognosis, probably caused by eosinophil-induced stimulation of tumor cells. The study was to investigate the effects of eosinophil cationic protein (ECP) on HL tumor cells in vitro. All cell lines were sensitive to ECP but to various degrees. At low concentrations of ECP, HDLM-2 was more sensitive than the L428 and particularly the KMH2 cell lines (Fig. 1). At higher concentrations the opposite was seen, with a more pronounced reduction in SI for L428 and KMH2 as compared to HDLM-2, where a plateau effect was seen.

For HDLM-2 (Fig. 1), a reduction in SI was evident at the lowest ECP concentration tested, 0.004 μM (p < 0.01). At a concentration of 0.018 μM, a plateau in SI of about 70% was reached. No statistically significant difference was determined from the concentration of 0.018 μM ECP and the higher ECP concentrations (ECP up to 1.14 μM) added, thus showing a true plateau.

In an additional experiment, HDLM-2 cells were incubated with or without ECP (LMW-ECP II at 0.07 μM) for 72 hours, after which a new serum-containing medium without ECP was added. Figure 2 shows HDLM-2 cells first after 72 hours of incubation with ECP, and then after an additional 72 hours of culture with serum. The cells continued to grow exponentially after the serum was added; this indicated that ECP caused no injury to the surviving HDLM-2 cells that affected their proliferation.

Fig. 1 The cytotoxic effect of LMW-ECP II on the cell lines HDLM-2 (filled circles), L428 (white squares), and KMH2 (filled triangles). (Glimelius I, et al., 2011)

Fig. 2 HDLM-2 cells cultured in 24-well plates with LMW-ECP II at a concentration of 0.07 μM for 72 hours. (Glimelius I, et al., 2011)