Rob,

I would imagine that mom would have lots of immune "memory" for past
antigens that would not be reflected in the breast milk sIgA.
Apparently, there is selective migration of lymphocytes to mammary
tissue.  Not all antigens that mom mounts an immune response to are
reflected in mammary sIgA.

Certainly, there is local manufacture of all antibody classes in the
breast, but again, there is selectivity in the response to antigens.
Gut sensitization in the mother is a hugely important source of
immunoactive cells, and thus through migration to the breast, antibodies
in breast milk, as well as colonization of the infant's gut.

For really state of the art info in lactation and immune function of the
mom and baby, I know that UAB is doing some wonderful work.  Connie
Carlysle - do you have anything else?

Having survived Georges on the muggy gulf coast of Alabama
Denise Sweeney, BSMT, IBCLC