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allogeneic bone marrow transplantation 31 alloimmunization
refers to organ or tissue grafts between genetically dissimilar
humans or unrelated members of other species.
allogeneic bone marrow transplantation
Hematopoietic cell transplants are performed in patients
with hematologic malignancies, certain nonhematologic
neoplasms, aplastic anemias, and certain immunodeficiency
states. In allogeneic bone marrow transplantation, the
recipient is irradiated with lethal doses to destroy malignant
cells or create a graft bed. The problems that arise include
graft-vs.-host disease (GVHD) and transplant rejection.
GVHD occurs when immunologically competent cells or
their precursors are transplanted into immunologically
crippled recipients. Acute GVHD occurs within days to
weeks after allogeneic bone marrow transplantation and
primarily affects the immune system and epithelia of the
skin, liver, and intestines. Rejection of allogeneic bone marrow
transplants appears to be mediated by NK cells and T
cells that survive in the irradiated host. Natural killer (NK)
cells react against allogeneic stem cells that are lacking self
major histocompatibility complex (MHC) class I molecules
and therefore fail to deliver the inhibitory signals to NK
cells. Host T cells react against donor MHC antigens in a
manner resembling their reaction against solid tissue grafts.
allogeneic disease
Pathologic consequence of immune reactivity of bone marrow
allotransplants in immunosuppressed recipient patients
as a result of graft-vs.-host reactivity in genetically dissimilar
members of the same species.
Mitogen
la Molecule
T cell AEF
B cell
Plasma cells
Allogeneic effect.
allogeneic effect
The synthesis of antibody by B cells against a hapten in the
absence of carrier-specific T cells, provided allogeneic T lymphocytes
are present. Interaction of allogeneic T cells with the
major histocompatibility complex (MHC) class II molecules of
B cells causes the activated T lymphocytes to produce factors
that facilitate B cell differentiation into plasma cells without
the requirement for helper T lymphocytes. There is allogeneic
activation of T cells in the graft-vs.-host reaction.
allogeneic graft
An allograft consisting of an organ, tissue, or cell transplant
from a donor individual or strain to a genetically different
individual or strain within the same species.
allogeneic inhibition
Homozygous tumors grow better when transplanted to
homozygous syngeneic hosts of the strain of origin than
they grow when transplanted to F1 hybrids between the
syngeneic (tumor) strain and an allogeneic strain. This
is manifested as a higher frequency of tumor and shorter
latency period in syngeneic hosts. The better growth of
tumor in syngeneic than in heterozygous F1 hybrid hosts
was initially termed syngeneic preference. When it became
apparent that selective pressure against the cells in a mismatching
environment produced the growth difference, the
phenomenon was termed allogeneic inhibition.
2.
Isograft
(genetically
identical)
1.
3.
Allograft
Types of grafts.
Autograft
Xenograft
allograft
An organ, tissue, or cell transplant from one individual or
strain to a genetically different individual or strain within
the same species. Also called homograft.
allogroup
Several allotypes representing various immunoglobulin
classes and subclasses inherited as a unit. Alleles that are
closely linked encode the immunoglobulin heavy chains in
an allogroup. An allogroup is a form of a haplotype.
alloimmune hemolytic anemia
Lysis of erythrocytes following exposure of an individual
to allogeneic red blood cells, which leads to the formation
of antibodies against foreign red blood cell antigens.
Transfusion reactions attributable to mismatched ABO
blood group antigens and Rh disease are examples.
alloimmune thrombocytopenia
Decreased blood platelets mediated by alloantibodies
against platelet surface antigens by a type II hypersensitivity
mechanism.
alloimmunization
An immune response provoked in one member or strain
of a species with an alloantigen derived from a different
member or strain of the same species. Examples include
the immune response of a human following transplantation
of a solid organ graft such as a kidney or heart.
Alloimmunization with red blood cell antigens in humans
may lead to pathologic sequelae such as hemolytic disease
of the newborn (erythroblastosis fetalis) in a third Rh(D) +
baby born to an Rh(D) – mother.
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