The Immunoglobulins of Mice. 4. Serum Immunoglobulin Changes Following Birth

SummaryThe changes in 7S γ2-, 7S γ1-, γ1A- and γ1M-immunoglobulin components following birth were studied in 3 mouse strains. Evidence for transfer of immunoglobulins via the placenta or yolk sac and via the colostrum and neonatal gastrointestinal tract were evaluated. Low levels of 7S γ2- and 7S γ1-globulins were found in the newborn indicating transplacental or yolk sac transfer of these proteins. Marked increase (to adult levels) of these 2 immunoglobulins occurred at 1 and 2 weeks of age. Both 7S γ2- and 7S γ1-globulins were present in the colostrum and appeared to be supplied via the gastrointestinal tract until 2 weeks of age. Subsequently, serum 7S γ2- and 7S γ1-globulin levels fell until age 4 weeks, when neonatal synthesis began to produce an increased serum level of these proteins. The γ1M (IgM)-globulins were detected in the serum at 1–3 weeks of age. The γ1A (IgA, β2A)-globulins were not detected in the serum until 4–6 weeks of age. Although γ1A-globulins are present in the colostrum, little o...