Untitled - D Ank Unlimited

graft arteriosclerosis 301 graft-vs.-host reaction (GVHR)
White graft
First set
Second set
graft arteriosclerosis
Intimal smooth muscle cell proliferation that occludes graft
arteries. It may occur 6 to 12 months following transplantation
and leads to chronic rejection of vascularized organ
grafts. It is probably attributable to a chronic immune
response to alloantigens of the vessel wall. It is also termed
accelerated arteriosclerosis.
graft facilitation
Prolonged graft survival attributable to conditioning of the
recipient with IgG antibody, which is believed to act as a
blocking factor. It also decreases cell-mediated immunity.
This phenomenon is related to immunologic enhancement
of tumors by antibody and has been referred to as immunological
facilitation (facilitation immunologique).
graft rejection
The immunologic destruction of transplanted tissues or
organs between two members or strains of a species differing
at the major histocompatibility complex (MHC)
for that species (i.e., HLA in humans and H-2 in mice).
The rejection is based upon both cell-mediated and
antibody-mediated immunity against cells of the graft by
the histoincompatible recipient. First-set rejection usually
occurs within 2 weeks after transplantation. The placement
of a second graft with the same antigenic specificity as the
first in the same host leads to rejection within 1 week and is
termed second-set rejection. This demonstrates the presence
of immunological memory learned from the first experience
with the histocompatibility antigens of the graft. When the
donor and recipient differ only at minor histocompatibility
loci, rejection of the transplanted tissue may be delayed,
depending upon the relative strength of the minor loci in
which they differ. Grafts placed in a hyperimmune individual,
such as those with preformed antibodies, may undergo
hyperacute or accelerated rejection. Hyperacute rejection of
a kidney allograft by preformed antibodies in the recipient
is characterized by formation of fibrin plugs in the vasculature
as a consequence of the antibodies reacting against
endothelial cells lining vessels, complement fixation,
polymorphonuclear neutrophil attraction, and denuding of
the vessel wall, followed by platelet accumulation and fibrin
0
2
5 days
4
6
7 to 8 days
8
10
Time of rejection (in days, after transplantation)
First Set rejection (skin graft rejection)
Types of skin graft rejection.
12 at 14 days
12
plugging. As the blood supply to the organ is interrupted,
the tissue undergoes infarction and must be removed.
graft-vs.-host disease (GVHD)
Disease produced by the reaction of immunocompetent
T lymphocytes of the donor graft that are histoincompatible
with the tissues of the recipient into which they have been
transplanted. Attributable to MHC or MiHA mismatching.
For the disease to occur, the recipient must be immunologically
immature, immunosuppressed by irradiation or drug
therapy, or tolerant to the administered cells. The grafted
cells must be immunocompetent. Patients develop skin
rash, fever, diarrhea, weight loss, hepatosplenomegaly,
and aplasia of the bone marrow. The donor lymphocytes
infiltrate the skin, gastrointestinal tract, and liver. The
disease may be either acute or chronic. Murine GVHD is
called runt disease, secondary disease, or wasting disease.
Both allo- and autoimmunity associated with GVHD may
follow bone marrow or hematopoietic stem cell transplantation.
Of patients receiving HLA-identical bone marrow
transplants, 20 to 50% still manifest GVHD, with associated
weight loss, skin rash, fever, diarrhea, liver disease,
and immunodeficiency. GVHD may be either acute, which
is an alloimmune disease, or chronic, which consists of both
allo- and autoimmune components. The conditions requisite
for the GVH reaction include genetic differences between
immunocompetent cells in the marrow graft and host tissues,
immunoincompetence of the host, and alloimmune
differences that promote proliferation of donor cells that
react with host tissues. In addition to allogenic marrow and
hematopoietic stem cell grafts, the transfusion of nonirradiated
blood products to an immunosuppressed patient
or intrauterine transfusion from mother to fetus may lead
to GVHD. GVHD is most common in bone marrow and
hematopoietic stem cell transplantation but rare in solid
organ transplants.
graft-vs.-host reaction (GVHR)
The reaction of a graft containing immunocompetent T
cells against alloantigens of the genetically dissimilar tissues
of an immunosuppressed recipient. Criteria requisite
for a GVHR include: (1) histoincompatibility between the
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