Evaluation of antigen-specific immunoglobulin responses in TACI-deficient mice. TACI-deficient mice (-/-), wild type (+/+) or heterozygous (+/-) littermates were immunized with type 3 PS [PS] (A) or type 3 PS-CRM197 conjugate [Conj] (B) and evaluated for PS specific serum antibodies by ELISA 2 weeks later. TACI-deficient or wild type littermates were immunized at weeks 0 and 2 with KLH [50 μg/mouse] (C), or DT-B [2 μg/mouse] (D), and evaluated for specific antibody at week 4 by ELISA. For PsaA-specific serum antibody responses, TACI-deficient, wild type, and heterozygous mice were immunized with 100 pmol of PsaA-BLyS fusion protein at week 0 (1°) and boosted with PsaA at week 3 (2°). Mice were bled at weeks 2 and 6 for the evaluation of primary (E) or secondary (F) PsaA-specific serum antibodies, respectively, by ELISA. Data are presented as means ± SEM for sera from individual mice (4-5 mice per group). In A-D A405 values for preimmune sera (diluted 1:100) were subtracted to generate specific absorbance for sera at 1:100 dilution.