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In mice following intranasal exposure to Streptococcus pneumoniae, protection against pneumococcal colonization was independent of antibody but dependent on CD4(+) T cells. Nonetheless, concentrations of antibodies to three conserved pneumococcal antigens correlated with protection against colonization. Concentrations of antibodies to conserved pneumococcal antigens may be correlates of protection without being effectors of protection.
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Trzciński et al. (2005) studied this question.
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