Methods
Ovine spleens and lymph nodes were sampled at day 16 of the estrous cycle, and at days 13, 16 and 25 of gestation, and qRT-PCR, Western blot and immunohistochemistry analysis were used to analyze the expression of the IκB family, including BCL-3, IκBα, IκBβ, IκBε, IKKγ, IκBNS and IκBζ. Early pregnancy induced expression of BCL-3, IκBα, IκBε, IKKγ and IκBζ, and expression of BCL-3, IκBβ and IκBNS peaked at day 16 of pregnancy in the spleen. However, early pregnancy suppressed the expression of BCL-3 and IκBNS, but stimulated the expression of IκBβ and IκBζ, and expression levels of IκBα, IκBβ, IκBε and IKKγ peaked in lymph nodes at days 13 and/or 16 of pregnancy. Early pregnancy changed the expression of the IκB family in the maternal spleen and lymph node in a tissue-specific manner, suggesting that the modulation of the IκB family may be involved in regulation of maternal functions of the spleen and lymph nodes, which are necessary for the establishment of maternal immune tolerance during early pregnancy in sheep.