Untitled - D Ank Unlimited

hematopoietic cells 316 hemolysin
marrow. Stromal cells, T cells, and other types of cells
regulate hematopoiesis.
hematopoietic cells
Erythrocytes and leukocytes.
hematopoietic cell transplant (HCT)
The inoculation of hematopoietic stem cells from the
peripheral blood, induced from the bone marrow, or occasionally
from umbilical cord blood of a histocompatible
donor into a recipient with an injured immune system.
hematopoietic chimerism
A successful bone marrow transplant leads to a state of
hematological and/or immunological chimerism in which
donor-type blood cells coexist permanently with host-type
tissues, without manifesting alloreactivity to each other.
Usually incomplete or mixed hematopoietic chimerism is
generated after bone marrow transplantation in which both
host-type and donor-type blood cells can be detected in
the recipient. Not only is immune reactivity against donor
type cells an obstacle to bone marrow engraftment, but
the problem of graft-vs.-host disease (GVHD) mediated by
donor T cells reactive against host antigens is also present.
Refer to chimera.
hematopoietic-inducing microenvironment (HIM)
An anatomical location in which the cells and cellular factors
requisite for the generation of hematopoietic cells may
be found.
hematopoietic lineage
A series of cells that develop from hematopoietic stem cells
and yield mature blood elements.
hematopoietic stem cell (HSC)
An undifferentiated bone marrow cell that serves as a
precursor for multiple cell lineages. A common pluripotent
hematopoietic precursor capable of self-renewal or commitment
to differentiation into the common myeloid precursor
that is the parent cell of a myeloid lineage (myelopoiesis)
or a common lymphoid progenitor that leads to cells of
the lymphoid lineage (lymphopoiesis). These cells are also
demonstrable in the yolk sac and later in the liver in the
fetus.
hematopoietic stem cell transplantation
Used to reconstitute hematopoietic cell lineages and treat
neoplastic diseases. Twenty-five percent of allogenic marrow
transplants in 1995 were performed using hematopoietic
stem cells (HSCs) obtained from unrelated donors.
Because only 30% of patients requiring allogenic marrow
transplants had siblings that were human leukocyte antigen
(HLA)-genotypically identical, it became necessary to identify
related or unrelated potential marrow donors. It was
found that complete HLA compatibility between donor and
recipient is not absolutely necessary to reconstitute patients
immunologically. Transplantation of unrelated marrow is
accompanied by an increased incidence of graft-vs.-host
disease (GVHD). Removal of mature T lymphocytes from
marrow grafts decreases the severity of GVHD but often
increases the incidence of graft failure and disease relapse.
HLA-phenotypically identical marrow transplants among
relatives are often successful. HSC transplantation provides
a method to reconstitute hematopoietic cell lineages with
normal cells capable of continuous self renewal. The
principal complications of HSC transplantation are GVHD,
graft rejection, graft failure, prolonged immunodeficiency,
toxicity from radio-chemotherapy given pre-and post-
transplantation, and GVHD prophylaxis. Methotrexate
and cyclosporin A are given to help prevent acute GVHD.
Chronic GVHD may also become a serious complication
that involves the skin, gut, and liver, and an associated sicca
syndrome. Allogeneic HSC transplantation often involves
older individuals and unrelated donors. Thus, blood stem
cell transplantation represents an effective method for the
treatment of patients with hematologic and nonhematologic
malignancies and various types of immunodeficiencies.
The in vitro expansion of a small number of CD34 + cells
stimulated by various combinations of cytokines appears
to produce hematopoietic reconstitution when reinfused
after a high-dose therapy. Recombinant human hematopoietic
growth factors (HGFs; cytokines) may be given to
counteract chemotherapy-treatment-related myelotoxicity.
HGF increases the number of circulating progenitor and
stem cells which is important for the support of high-dose
therapy in autologous and allogeneic HSC transplantation.
Both the bone marrow and umbilical cord blood serve as
sources for hematopoietic stem cells.
hematopoietic system
Those tissues and cells that generate peripheral blood cells.
hematopoietic tumor
The malignant transformation of immune system cells.
hematopoietins
Factors that facilitate the growth and development of
blood cells.
hematoxylin bodies
Nuclear aggregates of irregular shape found in areas of
fibrinoid change or fibrinoid necrosis in systemic lupus
erythematosus patients. These homogeneous-staining
nuclear masses contain nuclear protein and DNA, as well
as anti-DNA. They are probably formed from injured cell
nuclei that interacted with antinuclear antibodies in vivo.
Hematoxylin staining imparts a bluish-purple color to
hematoxylin bodies. They may be viewed in the kidneys,
lymph nodes, spleen, lungs, atrial endocardium, synovium,
and serous membranes. Hematoxylin bodies of the tissue
correspond to LE cells of the peripheral blood.
hematuria
Macroscopic or microscopic blood in the urine from any
cause, whether glomerular basement membrane injury or
renal stones, for example.
hemocyanin
A blood pigment that transports oxygen in invertebrates. In
immunology, hemocyanin of the keyhole limpet has been
widely used as an experimental antigen.
hemocytoblast
A bone marrow stem cell.
hemolymph
Invertebrate circulatory system liquid that conveys nutritious
molecules and waste products throughout the body of
the organism.
hemolysin
A complement-fixing antibody that lyses erythrocytes in
the presence of complement and acts with complement to
produce an interruption in the membrane integrity of red
blood cells, causing disruption. Historically, the term refers
to rabbit anti-sheep erythrocyte antibody used in the visible
part of a complement fixation test. Microbial products such
as streptolysin O may disrupt (lyse) red blood cells in agar
medium.