Immune effector responses to an excretory-secretory product of Giardia lamblia.

The prior immunisation of mice with purified excretory-secretory product (ESP) led to a complete failure of Giardia lamblia colonisation following challenge inoculation of these animals with trophozoites. The prior immunisation of mice with ESP resulted in a significant stimulation of local immunity as evidenced by a significant enhancement of T helper/inducer activity along with a significant increase in immunoglobulin A-bearing cells. Further, the presence of anti-ESP antibodies in the serum of immunised as well as immunised-challenged animals indicated the stimulation of the systemic lymphoid system. This suggests that the ESP is highly immunogenic and it could be one of the major antigens of G. lamblia responsible for protection against the infection.