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HLA type 337 homing
Wells for different Ab
+ lymphocytes + dye + complement
polymerase chain reaction (PCR) methodology and DNA or
oligonucleotide probes, especially for MHC class II typing.
Class I typing involves reactions between lymphocytes to
be typed with HLA antisera of known specificity in the
presence of complement. Cell lysis is detected by phase or
fluorescence microscopy. This is important in parentage
testing, disease association, transfusion practices, and transplantation.
HLA-A, -B, -C antigens should be defined by
at least one of the following: (1) at least two different sera
if both are monospecific, (2) one monospecific and two multispecific
antisera, (3) at least three multispecific antisera
if all multispecific types are used. Class II typing detects
HLA-DR antigens using purified B cell preparations. It
is based on antibody-specific, complement-dependent
disruption of the membranes of lymphocytes. Cell death is
demonstrated by the penetration of dye into the membrane.
Class II typing is more difficult than type II methods and
complement toxicity. At least three antisera must be used if
all are monospecific, and at least five antisera must be used
for multispecific sera.
HLA type
Both HLA class I and HLA class II allotypes expressed by
an individual.
HLA supertype
Human MHC alleles with overlapping peptide-binding
repertoires. The three HLA class I supertypes described
include A2, A3, and B7.
Hm-1
Designation for the Syrian hamster major histocompatibility
complex (MHC). MHC class II genes have been recognized.
Hodgkin disease
A type of lymphoma that involves the lymph nodes and
spleen, causing a replacement of the lymph node architecture
with binucleated giant cells known as Reed–Sternberg cells,
reticular cells, neutrophils, eosinophils, and lymphocytes.
Both lymphadenopathy and splenomegaly are present.
Patients manifest deficiencies of cell-mediated immunity that
cause tuberculin type skin tests to be negative. By contrast,
their B cell functions are not altered. They may exhibit
increases in suppressor cell activity and their susceptibility
to opportunistic infections is increased. Antigen-presenting
cells resembling dendritic cells apparently represent the
transformed cell type. Hodgkin lymphoma, characterized by
a predominance of lymphocytes, has a much better prognosis
HLA tissue typing.
Positive
Dead
cells
Negative
Live
cells
Hodgkin lymphoma; Hodgkin cell and Reed Sternberg cell.
than does the nodular sclerosis variety of the disease in
which the predominant cell type is nonlymphoid. Associated
with transformed germinal center B cells.
Hof
German word for courtyard that refers to the perinuclear clear
zone adjacent to the nuclei of plasma cells. Lymphoblasts and
Reed–Sternberg cells may also exhibit hof zones.
“hole in the repertoire” model
A concept that proposes that an animal failing to respond
to a given antigen is bereft of the requisite T cell specificity
attributable to tolerance mechanisms. The relevant foreign
peptide/self MHC combination is considered to closely
resemble a self peptide/self MHC combination in the
subject, leading to deletion of any T cell clones that would
respond to the antigen as autoreactive during negative selection
in the thymus or tolerization in the periphery. Thus, a
“hole” exists in the individual’s T cell repertoire compared
with the T cell repertoire of a responder.
holoxenic
An animal raised under ordinary conditions as opposed to
an axenic or gnotobiotic animal.
homeostasis
In immunology, the maintenance of a constant and physiologic
number of lymphocytes with a diverse repertoire even in
the presence of new lymphocytes and exponential expansion
of individual clones that follows immunogenic stimulation.
homing
The differential migration of lymphocytes or other leukocytes
to specific tissues or organs.
H