Trypanosoma cruzi infection was studied in mouse lines selected for maximal (AIRmax) or minimal (AIRmin) acute inflammatory reaction and for high (HIII) or low (LIII) antibody (Ab) responses to complex antigens. Resistance was associated with gender (females) and strain-the high responder lines AIRmax and HIII were resistant. The higher resistance of HIII as compared to LIII mice extended to higher infective doses and was correlated with enhanced production of IFN-γ and nitric oxide production by peritoneal and lymph node cells, in HIII males and females. We also analyzed the involvement of previously mapped Ab and T. cruzi response QTL with the survival of Selection III mice to T. cruzi infections in a segregating backcross [F1(HIII×LIII) ×LIII] population. An Ab production QTL marker mapping to mouse chromosome 1 (34.8 cM) significantly cosegregated with survival after acute T. cruzi infections, indicating that this region also harbors genes whose alleles modulate resistance to acute T. cruzi infection.