Intramuscular Immunization Induces Antigen-specific Antibodies in Urine

Abstract

Towards the development of vaccines against urinary tract infections (UTI), we determined the ability of intramuscular (i.m.) immunization to result in antigen-specific antibodies in urine. As a model antigen/vaccine, levels of total and vaccine-specific antibodies were determined in urine as a spin-out study of a phase 1 trial. Non–muscle-invasive bladder cancer (NMIBC) patients at different risks of progression, undergoing intravesical bacillus Calmette-Guérin (BCG) immunotherapy or not, received an adjuvanted recombinant protein vaccine that resulted in high titers of vaccine-specific serum immunoglobulin G (IgG) in all patients, regardless of the risk group. Vaccine-specific IgG and immunoglobulin A (IgA) were detected in urine of half of the patients at low risk of progression NMIBC and in all the intermediary/high- (int/high) risk patients. Vaccine-specific IgG titers were correlated to total urinary IgG levels, the latter being higher in the int/high-risk patients. In contrast, vaccine-specific IgA did not correlate to urinary IgA levels. Furthermore, vaccine-specific antibodies were transiently increased by intravesical BCG instillations. Altogether, our data show that a standard i.m. immunization can effectively induce antigen-specific antibodies in urine, which, upon selection of optimal vaccine targets, may provide protection against UTI. Vaccine-specific IgG titers were dependent on conditions affecting total urinary IgG levels, while production of vaccine-specific IgA in situ might independently contribute to protection against infections in the bladder. Patient summaryTowards the development of vaccines able to protect against urinary tract infections, we examined the potential of the intramuscular vaccination using a model antigen. We found two types of specific antibodies in the urine, which together may locally contribute to protection against infections, thus supporting the use of such a standard immunization route.