Patients with colorectal cancer were entered into a clinical phase I trial of immunotherapy with an autologous tumour cell/bacillus Calmette-Guerin (BCG) vaccine. We attempted to describe the possible effects and side effects of the immunisation, and further to investigate whether expression of immune-response-related surface molecules on the tumour cells in the vaccine correlated with survival. The first and second vaccine comprised of 107 irradiated tumour cells mixed with BCG, the third of irradiated tumour cells only. Thirty-nine patients were considered, but only 6 patients fulfilled the criteria for inclusion. No serious side effects were observed. With three years of observation time, two patients are healthy, while the rest have had recurrence, and two of them have died. In all vaccines, all tumour cells expressed HLA class I, some expressed HLA class II and none expressed CD80. There was an inverse relation between survival and HLA class II expression. This highlights an essential problem, in the absence of CD80 expression the expression of HLA class II may induce anergy. In future attempts to develop improved vaccines this problem should be addressed.

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