ABSTRACT
Surface and intracellular antigenic components of Giardia lamblia trophozoites were investigated using anti-giardia IgA and IgG antibodies from human milk and serum. Immunoperoxidase techniques were employed to identify these components with light and electron microscopy. Cryosections of trophozoites of G. lamblia were used with the purpose of allowing direct exposure of intracellular components in the light microscopy studies. Fixed trophozoites of this parasite were used for ultraestructural studies. The antigenic components that were linked with anti-Giardia IgA and IgG antibodies were located diffusely on the full extent of the parasite surface, mainly on the dorsal area. In the frozen section immunostaining was also found in the cytoplasm. Flagella and ventral surface were also immunoperoxidase positive. It is concluded that surface and intracellular antigens of G. lamblia trophozoites induce a human immune humoral response