Passive vaccination with IVIG protects against IPD in murine models of <i>S</i>. <i>pneumoniae</i> infection.

<p>Mice were passively vaccinated by i.p. administration of 12.8 mg of IVIG (Intratect) or PBS 3 hours before challenge with <i>S</i>. <i>pneumoniae</i>. (<b>A</b>) and <b>(B)</b> Concentration of human IgG measured by ELISA after <b>(A)</b> in mouse sera 3 h post-IVIG (n = 4), and (<b>B</b>) in mouse BALF recovered from mice 3 h post-IVIG and immediately before and at 2.5 and 24 h after i.n. challenge with 10⁷ CFU of TIGR4 strain <i>S</i>. <i>pneumoniae</i> (n = 4 to 6). <b>(C)</b> Correlation between concentration of murine albumin (mg/ml) and human IgG (μg/ml) in BALF 24 hr following invasive i.n. challenge in IVIG-treated mice (n = 6); <i>P</i> and r² values were calculated using the F test. <b>(D)</b> Bacterial CFU (log₁₀) recovered from BALF 2.5 hr following IN challenge with 5x10⁵ CFU of TIGR4 of IVIG-treated or PBS-treated control mice (n = 6 or 7). <b>(E)</b> Bacterial CFU (log₁₀) recovered from BALF, lung tissue or blood 24 hr following IN challenge with 10⁷ CFU of TIGR4 of IVIG-treated or PBS-treated control mice (n = 6). <b>(F)</b> Bacterial CFU (log₁₀) recovered from blood 4 hr following i.v. challenge with 5x10⁵ CFU of TIGR4 of IVIG-treated or PBS-treated mice (n = 5). <b>(G)</b> Effect of administration of i.v. 100 μl liposomal clodronate (5mg/ml) to mice on the numbers of F4/80+ve splenocytes measured by flow cytometry (n = 6), with data presented as means, error bars represent SDs, and <i>P</i> values were calculated using unpaired 2-tail Student t-test. <b>(H)</b> Effect of clodronate or PBS administration on bacterial CFU (log₁₀) recovered from the blood of IVIG-treated mice 4 hr following i.v. challenge with 5x10⁵ CFU of TIGR4 (n = 5). (<b>I)</b> Bacterial CFU (log₁₀) recovered from the lungs of neutrophil depleted mice (by prior treatment with the antiLy6 antibody 1A8) given either IVIG or PBS 24 hr and then inoculated i.n. with 5x10⁶ CFU of TIGR4 (n = 11 or 12). For <b>(A, B, D, E, F, H, I)</b>, symbols represent data from individual mice, bars represent group means, and <i>P</i> values were calculated using unpaired 2-tail Student t-test. Dashed lines represent the limit of detection.