Human recombinant lactoferrin as a new adjuvant in specific DNA vaccination against ErbB2 (75.2)

Abstract

Abstract Lactoferrin triggers several innate immunity mechanisms. Repeated oral administrations of a recombinant human lactoferrin (Talactoferrin, TLF, Agennix, Houston, TX) hamper the growth of both transplantable tumors and autochthonous mammary carcinomas arising in BALB/c mice transgenic for the rat ErbB2 oncogene (BALB-neuT mice). To evaluate the mechanisms that delay the tumor growth and enhance the immune response elicited by a DNA vaccine against rat ErbB2 oncogene, BALB-neuT mice received by gavage PBS or TLF (1 g/kg) once daily, 5 days per week, 3 weeks on and 1 week rest for seven cycles. Following oral TLF we observed: decrease of serum IL4 and IL5; increase of serum IL12 and IFNγ; decrease of immature myeloid cells in tumor draining lymph nodes. When BALB-neuT mice receiving oral TLF were vaccinated with 50 µg of DNA plasmid coding for the extracellular and transmembrane domain of rat ErbB2 we found: extended tumor-free survivals; increased overall survivals; decrease in the number of tumors/mouse; higher titers of vaccine-induced anti-ErbB2 antibodies; similar cytotoxicity activities against ErbB2+ tumors. These findings suggest that TLF is an interesting new adjuvant in DNA vaccination against ErbB2.