The production of
tumor-binding
antibodies was studied in a group of
cancer patients undergoing active specific
immunotherapy with irradiated,
cholesterol-treated, cell culture-derived autologous
tumor cells injected by the intralymphatic route. Fifteen patients were analyzed: nine patients (four
melanoma, one breast, one
sarcoma, one colon, and one undifferentiated
cancer) received three
injections of 10 to 15 x 10(6)
tumor cells, spaced 2 weeks apart, and six patients (two
melanoma, two renal, one breast, and one
colon cancer) received
tumor cells admixed with 3 x 10(6) U recombinant
interleukin-2 (IL-2) (
Proleukin, Cetus, Emeryville, CA, USA) plus a 10-day
intravenous infusion of 15 x 10(6) U/kg/day
IL-2 after each immunization. Serum antibody binding to autologous
tumor cells was measured at 2 and 4 weeks after initiation of
therapy using an
enzyme-linked
immunosorbent assay with patient serum being added to adherent
tumor cells bound to 96-well microtiter plates. After 4 weeks, we found a significant difference (0.02 less than P less than 0.04) in serum titer in the group receiving
IL-2 (33% mean increase) compared with the non-IL-2 group (8% mean increase). Although neither group showed clinical improvement in response to the
therapy, the results clearly demonstrated the efficacy of
IL-2 in augmenting patient antibody response to autologous intralymphatic
tumor cell immunization.