The effects of oral ingestion of different pesticides (
lindane,
phosalone,
carbaryl) and of a
polychlorinated biphenyl (
pyralene) on nonreaginic antibody production in BALB/c mice and also on the duration of Giardia muris
infection have been studied using the animal model of this disease. Only
lindane and
carbaryl produced significant effects on systemic antibody production following oral immunization with sheep red blood cells (SRBC).
Lindane ingestion led to a twofold increase in
IgG2b antibody titer to SRBC (P less than 0.05) and
carbaryl significantly increased both
IgG1 and
IgG2b titers. No reduction was seen in the synthesis of any
antibody class. The effect of feeding with
lindane was to increase the duration of
giardiasis significantly (P less than 0.002), and these mice developed systemic anti-Giardia
antibodies more frequently than Giardia-infected mice on normal diets. These results suggest that in the doses used these pesticides may increase systemic antibody responses to orally ingested
antigens, and by inference that spontaneous elimination of
giardiasis is independent of the systemic nonreaginic antibody response to the parasite.