In vitro Assessment of the Allergenicity of Novel Influenza Vaccine Produced in Dog Kidney Cells in Subjects with Dog Allergy

Abstract

RATIONALE: An inactivated influenza vaccine (Optaflu® is manufactured by Novartis, registered in the EU) produced in canine kidney cells (MDCK 33016-PF) contains no egg proteins and may be used for immunizing egg-allergic patients. Although no major dog allergens were identified in MDCK 33016-PF cells, minor dog allergens might be present and cause reactions in dog-allergic individuals. We sought to evaluate allergenicity of Optaflu in a passive sensitization assay.METHODS: RBL cells transfected with human IgE receptor-1 were sensitized with sera from adult dog-allergic subjects with positive skin prick tests to dog extract and detectable dog dander -IgE, and stimulated with serial dilutions of Optaflu and dog dander extract. N-hexosaminidase release% (NHR) was used as a marker of RBL degranulation. Western blots were performed and UniCAP was used to measure dog-specific IgE antibody levels.RESULTS: Median dog dander-IgE was 8.31 kUA/L (0.62; 67.9); median dog epithelium-IgE was 3.2 kUA/L, (0.4; 38.2). Median (range) maximum NHR (at 1st 10-fold dilution) was: 1). Optaflu- 0% (0; 1.4); 2). Dog dander-10.2% (0; 35.9), P < 0.001; and 3). Anti-IgE positive control-17.7% (1.2; 45.4). In a control egg-allergic subject, maximum NHR to a vaccine cultured in chick embryo and containing egg protein was 10.2%. IgE antibodies in pooled sera did not bind to Optaflu on immunoblots but produced strong binding to dog dander and epithelium extracts. Serum from a control egg-allergic subject strongly bound embryonated egg-derived vaccine.CONCLUSIONS: Optaflu, an influenza vaccine produced in continuous canine kidney cell line did not trigger degranulation in RBL cells passively sensitized with human anti-dog IgE. RATIONALE: An inactivated influenza vaccine (Optaflu® is manufactured by Novartis, registered in the EU) produced in canine kidney cells (MDCK 33016-PF) contains no egg proteins and may be used for immunizing egg-allergic patients. Although no major dog allergens were identified in MDCK 33016-PF cells, minor dog allergens might be present and cause reactions in dog-allergic individuals. We sought to evaluate allergenicity of Optaflu in a passive sensitization assay. METHODS: RBL cells transfected with human IgE receptor-1 were sensitized with sera from adult dog-allergic subjects with positive skin prick tests to dog extract and detectable dog dander -IgE, and stimulated with serial dilutions of Optaflu and dog dander extract. N-hexosaminidase release% (NHR) was used as a marker of RBL degranulation. Western blots were performed and UniCAP was used to measure dog-specific IgE antibody levels. RESULTS: Median dog dander-IgE was 8.31 kUA/L (0.62; 67.9); median dog epithelium-IgE was 3.2 kUA/L, (0.4; 38.2). Median (range) maximum NHR (at 1st 10-fold dilution) was: 1). Optaflu- 0% (0; 1.4); 2). Dog dander-10.2% (0; 35.9), P < 0.001; and 3). Anti-IgE positive control-17.7% (1.2; 45.4). In a control egg-allergic subject, maximum NHR to a vaccine cultured in chick embryo and containing egg protein was 10.2%. IgE antibodies in pooled sera did not bind to Optaflu on immunoblots but produced strong binding to dog dander and epithelium extracts. Serum from a control egg-allergic subject strongly bound embryonated egg-derived vaccine. CONCLUSIONS: Optaflu, an influenza vaccine produced in continuous canine kidney cell line did not trigger degranulation in RBL cells passively sensitized with human anti-dog IgE.