Depressed humoral immune responses to surface antigens of Giardia lamblia in persistent giardiasis

Abstract

The specific anti-plasma membrane- or surface-specific serum antibodies to Mr 82,000 antigen of Giardia lamblia trophozoites in cases of persistent and nonpersistent giardiasis in a pediatric population indicated significantly low concentrations of these antibodies in patients with persistent giardiasis. There was an insignificant difference in the amount of antibodies to whole trophozoite extract in persistent and nonpersistent giardiasis or asymptomatic carriers. The acute/nonpersistent cases had predominantly IgM class antigiardial antibodies, whereas persistent and asymptomatic carriers had antigiardial antibodies of the IgG class. The inability of persistent cases of giardiasis to clear infection appears to be related to low concentrations of antiplasma membrane/anti-Mr 82,000 antigiardial antibodies.