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immunodeficiency associated with hereditary 363 immunodeficiency with T cell neoplasms
immunodeficiency associated with hereditary
defective response to Epstein–Barr virus
An immunodeficiency that develops in previously healthy
subjects with normal immune systems who develop primary
Epstein–Barr virus infections. They develop elevated
numbers of natural killer cells in the presence of a lymphopenia.
The condition is serious, and its acute stage
may lead to B cell lymphoma, failure of the bone marrow,
or agammaglobulinemia. The disease may be fatal. The
condition was first considered to have an X-linked recessive
mode of inheritance recurring only in males, but it has
now been found in occasional females. The term Duncan’s
syndrome is often used to describe the X-linked variety of
this condition.
immunodeficiency, congenital
A varied group of unusual disorders with associated autoimmune
manifestations, increased incidence of malignancy,
allergy, and gastrointestinal abnormalities. These include
defects in stem cells, B cells, T cells, phagocytic defects,
and complement defects. An example is severe combined
immunodeficiency (SCID) due to various causes. The
congenital immunodeficiencies are described under the
separate disease categories.
immunodeficiency disorders
Conditions characterized by decreased immune function.
They may be grouped into four principal categories
based on recommendations from a committee of the
World Health Organization: antibody (B cell) deficiency,
cellular (T cell) deficiency, combined T cell and B cell
deficiencies, and phagocyte dysfunction. The deficiency
may be congenital or acquired. It can be secondary to an
embryologic abnormality or an enzymatic defect or may
be attributable to an unknown cause. Types of infections
produced and the physical findings are characteristic of
the type of disease. Screening tests identify a number of
these conditions, whereas others have unknown etiologies.
Antimicrobial agents for the treatment of recurrent
infections, immunotherapy, bone marrow transplantation,
enzyme replacement, and gene therapy are all modes of
treatment.
immunodeficiency from hypercatabolism of immunoglobulin
Serum levels of immunoglobulins fluctuate according to
their rates of synthesis and catabolism. Although many
immunological deficiencies result from defective synthesis
of immunoglobulins and lymphocytes, immunoglobulin
levels in serum can decline as a consequence of increased
catabolism or loss into the gastrointestinal tract or other
areas. Defective catabolism may affect one to several
immunoglobulin classes. For example, in myotonic dystrophy,
only IgG is hypercatabolized. In contrast to the normal
levels of IgM, IgA, IgD, IgE, and albumin in the serum, the
IgG concentration is markedly diminished. Synthesis of
IgG in these individuals is normal, but the half-lives of IgG
molecules are reduced as a consequence of increased catabolism.
Patients with ataxia telangiectasia and those with
selective IgA deficiency have antibodies directed against
IgA that remove this class of immunoglobulin. Patients with
the rare condition known as familial hypercatabolic hypoproteinemia
demonstrate reduced IgG and albumin levels
in the serum and slightly lower IgM levels, but the IgA and
IgE concentrations are either normal or barely increased.
Although synthesis of IgG and albumin in such patients is
within normal limits, the catabolism of these two proteins
is greatly accelerated.
immunodeficiency from severe loss
of immunoglobulins and lymphocytes
The gastrointestinal and urinary tracts are two sources of
serious protein loss in disease processes. The loss of integrity
of the renal glomerular basement membrane or renal
tubular disease or both may result in loss of immunoglobulin
molecules into the urine. Because the small IgG molecules
pass through in many situations, leaving larger IgA
molecules in the intravascular space, all immunoglobulins
are not lost from the serum at the same rate. More than 90
diseases that affect the gastrointestinal tract have been associated
with protein-losing gastroenteropathy. This may be
secondary to inflammatory or allergic disorders or disease
processes involving the lymphatics. In intestinal lymphangiectasia
associated with lymphatic blockage, lymphocytes
and proteins are lost. Lymphatics in the small intestine are
dilated. Intestinal lymphangiectasia patients show defects
in both humoral and cellular immune mechanisms. The
major immunoglobulins are diminished to less than half of
normal. IgG is affected more than IgA and IgM; they are
more affected than IgE.
immunodeficiency with B cell neoplasms
B cell leukemias can be classified as pre-B cell, B cell, or
plasma cell neoplasms. They include Burkitt’s lymphoma,
Hodgkin disease, and chronic lymphocytic leukemia (CLL).
Neoplasms of plasma cells are associated with multiple
myeloma and Waldenström’s macroglobulinemia. Many
of these conditions are associated with hypogammaglobulinemia
and a diminished capacity to form antibodies in
response to the administration of an immunogen. In CLL,
more than 95% of individuals have malignant leukemic
cells that are identifiable as B lymphocytes expressing
surface immunoglobulin. These patients frequently develop
infections and have autoimmune manifestations such as
autoimmune hemolytic anemia. CLL patients may have
secondary immunodeficiencies that affect both B and T
limbs of the immune response. Diminished immunoglobulin
levels are due primarily to diminished synthesis.
immunodeficiency with partial albinism
A type of combined immunodeficiency characterized by
decreased cell-mediated immunity and deficient natural
killer cells. Patients develop cerebral atrophy and
aggregation of pigment in melanocytes. This disease,
which leads to death, has an autosomal-recessive mode
of inheritance.
immunodeficiency with T cell neoplasms
Almost one third of patients with acute lymphocytic
leukemia (ALL), individuals with Sézary syndrome, and a
very few patients with chronic lymphocytic leukemia (CLL)
develop a malignant type of proliferation of lymphoid cells.
Sézary cells are poor mediators of T cell cytotoxicity, but
they can produce migration inhibitory factor (MIF)-like
lymphokines. Sézary cells produce neither immunoglobulin
nor suppressor substances, but they exert a helper effect for
immunoglobulin synthesis by B cells. In mycosis fungoides,
skin lesions contain T lymphocytes; an increase in
the number of null cells in the blood occurs with a simultaneous
decrease in the numbers of B and T cells. T cell
immunity is decreased, but IgA and IgE may be elevated.
Whereas ALL patients show major defects in cell-mediated
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