LACTNET Archives

Lactation Information and Discussion

LACTNET@COMMUNITY.LSOFT.COM

Options: Use Forum View

Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Paul Zimmer <[log in to unmask]>
Reply To:
Lactation Information and Discussion <[log in to unmask]>
Date:
Tue, 3 Sep 1996 10:47:30 -0500
Content-Type:
text/plain
Parts/Attachments:
text/plain (99 lines)
As promised, I am forwarding an abstract of my recent talk on lactation
and immunity.  Thanks to everyone on the list who provided references on
long-term consequences of breastfeeding - they really helped round out
one of my slides
-------------
OMaternal Regulation of the InfantOs Immunological DevelopmentOJ. Paul
Zimmer, Ph.D.Developmental and Clinical ImmunologyUniversity of Alabama
at Birmingham   The success of a childOs postpartum health and
immunological development depends heavily on maternally-acquired
immunity.  The lactating mother's immune system adapts to a unique state
where immunological factors are produced and secreted without any
apparent benefit for the motherOs health.  Changes in the mother's
humoral immune system may be most significant in this respect because
antibodies produced by maternal B-cells play a significant role in the
health of the fetus and neonate.        Maternal B-cell lymphopoeisis in the
bone marrow virtually shuts down during the later stages of pregnancy.
The resumed production of newly-formed B-cells is delayed by lactation
as seen in our own studies of the mouse and, in humans, the correlation
between maternal peripheral blood B-cell relative frequencies and her
breastfeeding behavior (Zimmer, et al, 1996).  At the same time, mature
B-cells are homing to the mammary tissue from the gut and other mucosal
surfaces to provide a secreted antibody repertoire in the milk
reflective of the pathogens present in the motherOs local
environment.    These maternal immunological adaptations have immediate,
short- and long-term effects on the infantOs immunological health.  The
most immediate benefit is that secreted milk antibodies reduce the
infectivity of pathogens that reach the childOs oral and nasal mucosa
and thereby reduce the risk of childhood diarrheal and respiratory tract
infections.  Human milk actively promotes the childOs early
immunological development as reflected in the apparently increased
production of urinary secretory IgA (sIgA) by breastfed compared to
formula-fed infants.  In the absence of maternally-derived immunity,
mouse pups have aberrant maturation of their mucosal immunity and
inappropriate antibody responses to gut microflora (Kramer and Cebra,
1995).  In the long-term, adults who were breastfed as children benefit
from a reduced risk of some cancers, allergies and autoimmune
disorders.      Maternal immune status can determine whether
maternally-acquired immunity has a beneficial or detrimental
immunological outcomes in the child.  In addition to the passive
immunity provided by milk antibodies, it has been proposed that
specialized milk antibodies, called anti-idiotypic antibodies, immunize
the infant against infections by binding to and activating B-cells at
the childOs mucosal surfaces.  On the other hand, high titres of
maternal antibodies can impair the offspringOs ability to produce its
own antibodies in response to immunizations.  If maternally-derived
antibodies bind to subsets of B-cells thought to play a key role in the
ontogeny of the antibody repertoire, the offspringOs ability to mount
appropriate immune responses to certain antigens may be abolished for
life (Vakil, et al, 1986).  Thus, inadequate, inappropriate or excessive
transfer of antibody to the offspring can impair the optimal
immunological  benefits the child receives from the mother.
Unfortunately, immunizing the mother to produce an optimal titre of
antibody in the milk has met with mixed results and appears to depend on
immunization route and whether the mother has been naturally exposed to
the immunogen.   Maternal immunological adaptations may be dependent upon
maternal demographic characteristics, and the present state of knowledge
indicates maternal parity is most significant in this respect.
Multiparous women appear to produce more sIgA and lysozyme in their milk
compared to primiparous women.  What has not been adequately addressed
is the effect of maternal age on milk immune composition and the
immunological development of the offspring.  Given the widely different
physiologies of a mother at 16 versus a mother at 46 years of age, it is
surprising that no specific research has been done to address this
issue.  Without additional research on the roles of parity and age, our
understanding of normal variation in maternally-derived immunity will be
deficient.      Variations in maternal nutritional status during pregnancy or
lactation also change the immunological composition of milk and/or have
significant impact on the child's immunological development.  Lactating
women with a moderate degree of malnutrition (reflected in low
weight-for-height) have reduced concentrations of colostrum sIgA and
other milk immunoproteins compared to well-nourished women.  Provision
of dietary supplements appears to reverse this deficit.  When mice are
deprived of zinc during gestation and lactation, B-cell development in
the offspring is severely impaired and these effects can persist for
generations (Beach, Gershwin and Hurley, 1981).  Cross-fostering
experiments show that these effects can be induced by fostering
zinc-replete mice on deficient dams and partially reversed by fostering
deficient mice on zinc-replete dams (Beach, Gershwin and Hurley, 1983).
Gestational vitamin B6 deficiency also appears to impair immune system
development and the effects may persist into adulthood (Davis, 1974).
Given the potential for severe, long-lasting effects of maternal
micronutrient deficiency on the ontogeny of the offspring's immune
system, a better understanding of nutrient-immune interactions at the
mother-child interface is essential for determining micronutrient
requirements during pregnancy and lactation.     In summary, the maternal
immune system undergoes unique adaptations to produce immune factors for
transmission to the fetus and neonate.  These factors can reduce the
risk of neonatal infections, promote the maturation of the neonate's
immune system and have a significant role in the long-term health of the
offspring.  Changes in maternal characteristics such as immune status,
parity or nutritional status can modify, diminish or even reverse such
benefits.  Thus, efforts to promote child health will benefit from
enhancing the mother's role in the process.Selected ReferencesBeach, RS,
Gershwin, ME and LS Hurley.  Science  1981, 218: 469-471.Beach, RS,
Gershwin, ME and LS Hurley.  Am J Clin Nutr  1983, 38: 579-590.Davis, S.
 Nature 1974, 251: 548-550.Kramer, DR and JJ Cebra.  Internat Immunol
1995, 7: 911-918.Vakil, M, et al.  Eur J Immunol 1986, 16:
1159-1165.Zimmer, et al.  J Reprod Immunol 1996, 30: 81-95.

ATOM RSS1 RSS2