[LAK cells and immunotherapy of cancer]

Cancer immunotherapy still appears very unsatisfactory in humans. However, it has been shown recently that Interleukin 2 (IL2) could be used to generate, in vitro as well as in vivo, a new anti-tumoral activity directed against fresh tumor cells, allogenic as well as autologous, both of leukemic and solid tumor origin. This activity is not connected with the NK activity, but with a lymphocyte sub-population termed 'Lymphokine Activated Killer (LAK) Cells'. The exact nature of these LAK cell precursors is still a matter of controversy: 'nul' lymphocyte, T or NK markers bearing lymphocytes, or different precursors according to the system of activation that has been used. However, after being activation, these LAK cells always express T cell-markers. The activation has a very short lifespan, explaining the need for a prolonged contact of the cells with IL2, and therefore the necessity to continue injecting the lymphokine in vivo. The clinical results that have been reported so far are still very preliminary. The most common treatment protocol consists of 5 days of IL2 injections followed by 5 days of leukapheresis and in vitro activation of the collected cells, and then auto-transfusion of the activated cells and IL2 during the next 5 days. The clinical toxicity encountered is impressive in terms of frequency as well as severity. Clinical activity seems to be relatively weak. Nevertheless, the concept still appears to be very promising.