Induction of antibodies to a tumor-associated antigen by immunization with a whole melanoma cell vaccine

Urinary-tumor-associated antigen (U-TAA) is a glycoprotein present in the urine of melanoma patients. Previous studies have addressed the role of U-TAA in immunoprognosis. The present investigation was undertaken to determine whether the administration of whole melanoma cell vaccine (MCV) could induce the formation of anti-(U-TAA) antibodies in melanoma patients. The subjects of this study were stage II and III melanoma patients receiving MCV alone or in conjunction with cyclophosphamide. Anti-(U-TAA) IgM and IgG antibody levels were determined by enzyme immunoassay in sequential serum samples from 15 stage II and III melanoma patients receiving MCV. U-TAA purified from the urine of a melanoma patient was used as a target in this assay. The mean anti-(U-TAA) IgM titer prior to vaccination was similar to that of a non-vaccinated melanoma control group (1:1138±214, n=15 vs 1:1334±254, n=7; P=0.375) but prevaccination IgG levels were generally higher than in the control group (1:3984±602 vs 1:2595±423; 0.1>P>0.05). While only 6 of the 15 patients demonstrated a rise in levels of IgG antibodies (mean 1:2964±1047 pre-MCV to 1:9958±2677 post MCV, P<0.01), 11 of the 15 patients demonstrated a greater than twofold rise in their anti-(U-TAA) IgM titers following vaccination (1:1051±259 pre-MCV to 1:2518±576 post-MCV; P<0.005). In addition, patients with visceral metastases consistently elicited anti-(U-TAA) responses equivalent to those with more limited disease. Concomitant administration of cyclophosphamide did not affect the response rates or peak antibody levels. The possibility that these antibody responses were actually against histo-compatibility locus antigens (HLA) (contaminating our U-TAA preparation) was ruled out because the target antigen (U-TAA) was devoid of HLA, and because the induction of anti-(U-TAA) antibodies did not correlate with the induction of anti-HLA antibodies. These results demonstrate augmentation of anti-(U-TAA) IgM and IgG antibodies by immunization with the MCV.