FIGURE 3. Diminished immunoglobulin production in Blm^f/Δ Cre mice.

(A) Serum Ig isotype concentrations from 7–10 week old naive Blm^f/Δ Cre (n = 8–13) and littermate control mice (n = 14–19) were measured by ELISA. Each data point represents an individual animal and horizontal bars denote mean concentrations for each group and isotype (IgM: p = 10⁻⁴, IgG3: p = 2 × 10⁻⁸, IgG1: p = 10⁻⁶, IgG2b: p = 10⁻⁶, IgG2a: p = 10⁻⁴, IgA: p = 0.001).

(B) TI immune responses after primary and secondary immunizations. 12–17 week old Blm^f/Δ Cre and control mice were intraperitoneally immunized with 10 µg NP₄₁-Ficoll in PBS on weeks 0 and 17, and NP-specific serum IgM and IgG3 levels were determined after 0 (pre-immune), 1, 2, 3, 18, 19, and 20 weeks by ELISA. Average concentrations (± SD) for each group are expressed relative to a pool of reference sera that were immunized using the same protocol (n = 7–10 for sera collected after 0–3 and n = 4 for sera obtained after 18–20 weeks). Broken lines represent the detection limit of the ELISA (*p < 0.05, **p < 0.005, ***p < 0.0005 by Mann-Whitney test).

(C) TD immune responses after primary and secondary immunizations. Cohorts of 11–19 week old Blm^f/Δ Cre and control mice immunized i.p. with 10 µg NP₂₅-CGG in alum on weeks 0 and 10 were bled on weeks 0, 1, 2, 3, 11, 12, and 13. NP-specific serum IgM, IgG1, and IgG2a titers were determined by ELISA and analyzed as in (B). For each group, seven and five mice were analyzed on weeks 0–3 and 11–13, respectively.

(D) Frequencies (± SD) of NP-specific IgM-, IgG1-, and IgG2a-secreting AFCs in the bone marrow of four Blm^f/Δ Cre and five control mice 12–13 weeks after secondary immunization with NP₂₅-CGG as determined by ELISPOT. The mice were part of the cohort shown in (C). Statistical analysis was performed as in (B).