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maternal antibodies 482 matrix metalloproteinases (MMPs)
Protein Solution
in Low Concentration
Attachment
to receptors
Microvilli
Phagosome
Lysosome
Fusion and
digestion
Phagolysome
releasing
undigested protein
from cell
membranes. The passively administered antibodies become
bound to the glomerular basement membrane, fix complement,
and induce glomerular basement membrane injury
with increased permeability. Neutrophils and monocytes
may infiltrate the area. Masugi nephritis is an experimental
model of Goodpasture’s syndrome in humans. Also called
nephrotoxic nephritis.
maternal antibodies
Maternal immunoglobulins are passed to offspring both
in utero and in the neonatal period. In humans, immunoglobulin
G (IgG) is transferred by way of the placenta as
early as the 38th day of gestation. Transfer remains stable
until the 17th week and then increases until term. Only the
IgG class of antibodies crosses the placenta. The SC portion
of the immunoglobulin is bound to specific placental
membrane receptors of the Scγ type III variety (CD16) that
possess binding sites for the Foc region of IgG in addition
to epitopes that can be recognized by the antigen-binding
site of IgG. The receptors have low affinity for aggregated
or complex IgG, with the strongest affinity for IgG 1 and
IgG 3, less for IgG 4, and least for IgG 2; they have no affinity
for IgM and IgA. The receptors are concentrated on syncytiotrophoblasts
that make direct contact with the mother’s
circulation. Human colostrum and fresh breast milk contain
numerous specific and nonspecific host resistance factors.
Secretory IgA is present in these fluids, with the highest
concentration in colostrom that peaks during the first
34 days postpartum. Breast-fed children receive 0.5 g of
secretory IgA per day. Human milk also contains IgG and
IgM, as well as secretory IgA but in lower concentrations.
Factors other than immunoglobulins that protect against
infections include lactoferrin that acts as a bacteriostatic
agent depriving microbes of iron. Lysozyme is also present
in milk. Breast milk also contains macrophages, T and B
Protein Solution
in High Concentration
(a) (b)
Maternal antibodies.
Attachment
to receptors
Microvilli
Phagosome
Lysosome
Fusion and
digestion
Phagolysome
releasing
undigested protein
from cell
cells, neutrophils, epithelial cells, and immunomodulators.
Diseases caused by maternal antibodies are listed individually.
Refer also to Brambell receptor.
maternal immunity
Passive immunity conferred on the neonate by its mother.
This is accomplished prepartum by active immunoglobulin
transport across the placenta from the maternal to the fetal
circulation in primate animals including humans. Other
species such as ungulates transfer immunity from mother to
young via antibodies in the colostrum, as the intestine can
pass immunoglobulin molecules across its surface in the
early neonatal period. The egg yolk of avian species is the
mechanism through which immunity is passed from mother
to young.
maternal immunoglobulins
Refer to maternal antibodies.
maternal imprinting
Alteration of the maternal allele chromatin of a gene in
a subject to render it more likely to be expressed than
the paternal allele. Concerns the relationship between a
disease-related allele and the incidence of the disease.
matrix (HIV)
Provides the scaffolding that the viral envelope enfolds.
matrix metalloproteinases (MMPs)
A family of zinc-containing endoproteinases that adjust
specific components of extracellular matrix, thereby
contributing to matrix equilibrium and structural integrity.
They are grouped in three categories: (1) interstitial collagenases,
(2) stromelysins, and (3) gelatinases. Dysregulation
of MMP synthesis and activation is believed to contribute
to tissue injury in inflammatory and neoplastic diseases.
Macrophages, T lymphocytes, eosinophils, and neutrophils
all produce MMPs with cell-specific patterns. MMPs from
macrophages contribute to the degradation, removal, and