Selective transfer of IgG1 into milk of ewes following inhibition of milk secretion or acute inflammation.

Selective transfer of IgG1 into milk and levels of sodium and potassium in milk of lactating ewes were followed before and after intramammary infusion of colchicine or alpha-haemolysin. Milk production decreased substantially following infusions and the ionic composition of milk changed such that levels of sodium increased and of potassium decreased. By 3-4 days after infusions milk production had increased to approach pre-infusion levels and levels of sodium and potassium had returned to pre-infusion values. Selective transfer of IgG1 into milk was enhanced following inhibition of milk production but decreased following the acute inflammation induced by alpha-haemolysin. The results of these experiments are consistent with the view that, in the ruminant, selective transfer of IgG1 into mammary secretion is inversely related to the synthetic activity of the alveolar epithelium. Associated with enhanced selective transfer of IgG1, substantial changes occur in the ionic composition of milk. Moreover, acute inflammation of the mammary gland impairs selective transfer of IgG1 into milk, but during recovery from inflammation selective transfer of IgG1, is enhanced. The latter phenomenon may be functionally significant for recovery from intramammary infection.