Ascaris suum: homocytotropic antibody responses in mice.

Homocytotropic antibodies in the sera of CD-1 and DBA/1 mice infected with larval A. suum were titered by PCA reactions. IgG₁ and reaginic antibody responses were similar in both strains of mice. With a dose of 8000 to 10,000 embryonated eggs, reaginic antibody was detected during the second week and IgG₁ antibody during the third week of infection. Doses of 1500 to 5000 eggs gave delayed antibody responses or did not induce a detectable response, although an anamnestic response followed a challenge inoculation even when no detectable antibody was observed in initial infection. Larval A. suum infections in two strains of mice did not potentiate a reaginic response to ovalbumin.     

Induction of mouse homocytotropic antibodies to Timothy pollen antigens.

The IgG1 and IgE homocytotropic antibody responses of LAF and C3H mice to timothy pollen antigens are defined. Both mouse strains responded to low doses of crude timothy pollen extract (WST) or a major antigen of timothy pollen coupled to a purified fraction of Ascaris suum (Antigen B-Ascaris). Titers in LAF mice were greater than those in C3H mice. Regardless of the immunogen, antigen B was the major determinant recognized by the homocytotropic antibodies; PCA titers with WST or antigen B for challenge were equivalent and PCA activity could be inhibited by antigen D, a dialyzable fraction of timothy pollen possessing the antigen B determinant in monovalent form. The possible usefulness of antigen D for in vivo and in vitro studies of specific immune suppression of cellular activity is discussed.