HUMORAL RESPONSE AGAINST HEAT-SHOCK PROTEINS AND OTHER MYCOBACTERIAL ANTIGENS AFTER INTRAVESICAL TREATMENT WITH BACILLE CALMETTE-GUERIN (BCG) IN PATIENTS WITH SUPERFICIAL BLADDER-CANCER

Few studies have analysed the antibody response during intravesical BC G immunotherapy for superficial bladder cancer. We have examined the e volution in serum antibody response against several heat shock protein s (hsp), including the recombinant mycobacterial hsp65 and the native protein P64 from BCG, GroEL from Escherichia coli (hsp60 family), reco mbinant mycobacterial hsp70 and the E. coli DnaK (hsp70 family), again st purified protein derivative of tuberculin (PPD) and the AG85 comple x of Mycobacterium bovis BCG, as well as against tetanus toroid in 42 patients with a superficial bladder tumour, 28 treated with six intrav esical BCG instillations and 14 patients used as controls. We also ana lysed the lymphoproliferative response of peripheral blood mononuclear cells against PPD in this population. Data of antibody responses at 6 weeks post BCG were available in all 28 patients, and at 4 month foll ow up in 17 patients. All patients who demonstrated a significant incr ease in IgG antibodies against PPD at 4 months follow up had a signifi cant increase already at 6 weeks of follow up. In contrast, IgG antibo dies against hsp increased significantly from 6 weeks to 4 months post -treatment. A significant increase in IgG antibodies against PPD, hsp6 5, P64, GroEL, and hsp70 at 4 months follow up was observed in 10/17, 8/17, 10/17, 4/17 and 8/17 patients. Native P64 protein elicited a hig her antibody response than recombinant mycobacterial hsp65. No increas e in antibody response was observed against Dnak from E. coli, against AG85 or tetanus toroid after BCG therapy. An increase in IgG antibodi es against P64 at 4 months follow up compared with pretreatment Values was found to be a significant predictor of tumour recurrence (P < 0.0 1). Further studies with a larger number of patients are needed to con firm the value of the antibody response against P64 as a clinical inde pendent prognostic factor.