Mixed organ culture as a tool for considering cellular tumor-host relationships in tumor patients

A method is reported for considering tumour-host relationships, which consists in cultivation of human tumours jointly with autologous lymphocytes in an organ culture system and determining separately tumour and lymphocyte DNA synthesis before and after mixed culture. Some experiments explore variables of the new system. For mixed organ cultures the best conditions are: 4-day incubation, lymphocyte DNA ratio to tumour cell DNA less than 9:1 (2-10(6) lymphocytes/ml) and autologous serum. So far 41 tumours (20 mammary, 17 gastric, and 4 bronchial carcinomas) have been examined. 22 tumours showed satisfactory in vitro maintenance. In 50% of the mixed organ cultures, lymphocyte DNA synthesis proved to be higher than in lymphocyte control cultures. Blast counts in the cell smears are in good accord with results obtained by biochemical determination of DNA synthesis. 7 of the tumours studied have shown a pronounced reduction of DNA synthesis in the presence of lymphocytes. The present results underline the individuality of tumour-host relationships and suggest the necessity of determinations of the immune reactivity in cancer patients. Advantages and disadvantages of the method are discussed.