In vitro synthesized immunoglobulin A from nu/+ and reconstituted nu/nu mice against a dominant surface antigen of Giardia lamblia.

Nu/+ mice (ZU.ICR-strain) experimentally infected with Giardia lamblia (clone GS/M-83-H7) cleared the infection by day 45 postinfection (p.i.). Athymic nu/nu mice were reconstituted with immune Peyer's patch lymphocytes obtained from self-healed nu/+ littermates and thus acquired the potential to decrease their intestinal parasite mass. Intestinal B-cells from self-healed nu/+ mice as well as from immune-reconstituted athymic nude mice synthesized in vitro parasite-specific immunoglobulin A (IgA). This IgA was subsequently analyzed by immunoblotting, showing a predominant reaction with the major surface antigen (a 72,000-Da polypeptide) characterizing the Giardia clone in question. The hypothesis on the causative role of intestinal IgA and immune lymphocytes in the control of G. lamblia infection thus deserves further attention.