Biotechnology Letters 24: 1515–1518, 2002. © 2002 Kluwer Academic Publishers. Printed in the Netherlands. 1515 Vitamin A as adjuvant to the mouse immune response to pertussis, tetanus and diphtheria vaccines Waldely O. Dias ∗ , Denise S.P.Q. Horton, Vera C.B. Cainelli Gebara, Noemi Furuyama, Luciana Risol´ eo, Vera R.F. Ferreira & Isaias Raw Centro de Biotecnologia, Instituto Butantan, Avenida Dr. Vital Brasil, 1500, 05503-900 São Paulo, SP, Brasil ∗ Author for correspondence (Fax: +55 11 3726 1505; E-mail: waldely@globalvip.com.br) Received 24 April 2002; Revisions requested 10 May 2002; Revisions received 9 July 2002; Accepted 11 July 2002 Key words: adjuvant, diphtheria, pertussis, tetanus, vitamin A Abstract Vitamin A was used as adjuvant, comparatively with Al(OH) 3 , in pertussis, tetanus and diphtheria vaccines. Both groups induced a primary immune response in mice, and one single booster dose elevated the antibodies titers in average 554 times to vitamin A groups and 104 times to Al(OH) 3 . These antibodies titers correlate with sera IL-4 in immunized animals, suggesting a Th2 response. Other cytokines detected in the sera and/or lymphocytes culture supernatants (IL-2 and IFN-) indicated that vitamin A could also modulate a Th1 response in DPT and acellular pertussis vaccines. Introduction Vitamin A is considered as an anti-infective agent (Ross 1992) and is required in several processes re- lated to cellular and humoral immunity (Ross & Häm- merling 1994). The primary antibody responses of vitamin A-deficient rats were very low after immu- nization with protein antigens but were restored by supplementation with vitamin A before immuniza- tion (Ross 1996). In the developing world, vitamin A deficiency in young children is associated with up- per respiratory tract infections, measles and diarrhea (Hussey & Klein 1990). Administration of vitamin A increased the immune response of vitamin A-deficient infants (Semba 1994). The World Health Organiza- tion’s Expanded Program on Immunization has recom- mended vitamin A supplements together with measles vaccination (Ross 1995). In the present work we studied the mice immune response to pertussis, tetanus and diphtheria vac- cines administered as a mixture with a commercial preparation of vitamin A. Materials and methods Immunization schedule Groups of 10 male Swiss mice were immunized (0.5 ml dose -1 – intraperitoneal) with whole cell pertussis vaccine (1/25 human dose), acellular per- tussis vaccine prepared as previously described (Dias et al. 1994), diphtheria-pertussis-tetanus vaccine (DPT) (1/25 human dose) or diphtheria-tetanus vac- cine (DT) (1/25 human dose). All antigens were produced at Instituto Butantan. The antigens were in- jected as a mixture with Arovit (Roche – 24.7 mg retinol palmitate per dose), referred in the text as vi- tamin A, or Al(OH) 3 (0.5 mg per dose). A booster was given under the same conditions 22 days after the first injection. All the animals were bled by retro- orbital puncture at days 7, 14, 21 and 36 after the first immunization. Antibody titration The sera from each group of animals were pooled and tested against purified pertussis toxin (PT), tetanus and diphtheria toxoids, by a modified enzyme-linked