AJP - Endocrinology and Metabolism, Vol 251, Issue 2 227-E233, Copyright © 1986 by American Physiological Society
Transfer of protein antigens into milk after intravenous injection into lactating mice
P. R. Harmatz, D. G. Hanson, M. K. Walsh, R. E. Kleinman, K. J. Bloch and W. A. Walker
We investigated the transfer of bovine serum 125I-albumin (125I-BSA),
bovine 125I-gamma-globulin (125I-BGG), 125I-ovalbumin (125I-OVA), and
125I-beta-lactoglobulin (125I-BLG) from the blood into the milk of
lactating mice. Equal amounts (by weight) of the radiolabeled proteins were
injected intravenously into mice 1 wk postpartum. Total radioactivity,
trichloroacetic acid-precipitable radioactivity, and specifically
immunoprecipitable radioactivity were measured in serum, mammary gland
homogenate, and milk. Clearance of immunoreactive OVA (iOVA) and iBLG from
the circulation was more rapid than iBSA and iBGG. The radioactivity in
mammary tissue associated with BSA and BGG was greater than 70%
immunoprecipitable throughout the 4-h test interval; 125I-OVA and 125I-BLG
were less than 12% precipitable 1 and 4 h after injection. In milk obtained
at 4 h, there was an approximately 10-fold greater accumulation of iBSA or
iBGG than of iOVA or iBLG. These experiments demonstrate that protein
antigens differ in their ability to transfer from maternal circulation into
milk. The transfer into milk appeared to be in proportion to persistence of
the antigens in the maternal circulation.
