In vitro sensitivity of immature human mast cells to chemotherapeutic agents

Cells from the human immature mast cell line, HMC-1, were tested for their sensitivity to 11 chemotherapeutic agents by changes in viability and incorporation of tritiated thymidine ([³H]-thymidine) after 72 h of in vitro drug exposure. Doxorubicin hydrochloride and cytosine arabinoside were the most active agents against HMC-1 cells at the concentrations tested. Doxorubicin hydrochloride inhibited the incorporation of [³H]-thymidine and decreased the viability of HMC-1 cells by >90% at a concentration of 0.06 μg/ml. Cytosine arabinoside inhibited the incorporation of [³H]-thymidine and decreased the viability by >95% at a concentration of 0.1 μg/ml. A clone of HMC-1 cells, A₄, with an enhanced percentage (70-80%) of metachromatically staining cells was equally sensitive to these two agents; however, A₄ cells were more sensitive to vinblastine sulfate and less sensitive to methylprednisolone than was the parent cell line. Both HMC-1 cells and A₄ cells showed approximately equal sensitivity to etoposide and to mitomycin. These results show that human mast cells are susceptible in vitro to a number of commonly used chemotherapeutic drugs.