Untitled - D Ank Unlimited

hypogammaglobulinemia of infancy 348 H-Y system
disease, a congenital type, and an acquired type such as
in chronic lymphocytic leukemia. Human γ globulin is
used for treatment.
hypogammaglobulinemia of infancy
A temporary delay in immunoglobulin synthesis during
the first 12 or even 24 months of life. This delay leads only
to a transient physiologic immunodeficiency following
catabolism of maternal immunoglobulins passed to the
infant.
hyposensitization
A technique to decrease responsiveness to antigens acting
as allergens in individuals with immediate (type I) hypersensitivity
to them. Because the reaction is mediated by
immunoglobulin E (IgE) antibodies specific for the allergen
becoming fixed to the surface of the patient’s mast cells, the
aim of this mode of therapy is to stimulate the production of
IgG-blocking antibodies that will combine with the allergen
before it reaches the mast cell-bound IgE antibodies. This is
accomplished by graded administration of an altered form
of the allergen that favors the production of IgG rather than
IgE antibodies. In addition to intercepting allergen prior to
its interaction with IgE, the IgG antibodies may also inhibit
further production of IgE. The subcutaneous inoculation
of progressively increasing quantities of purified allergen
on a regular basis for 3 to 5 years leads to the synthesis
of allergen-specific IgG4, which fails to trigger mast cell
degranulation instead of the production of allergen-specific
IgE.
hypothalamic–pituitary–adrenal (HPA) axis
The neural system pathway that is responsible for the “fight
or flight” acute stress response. Activation of the HPA by
extreme stress leads to excessive glucocorticoid synthesis,
suppressed inflammatory responses, and increased susceptibility
to infections.
hypothyroid
Markedly diminished synthesis of thyroid hormone by the
thyroid gland.
H-Y antigen
An epitope detected by cell-mediated and humoral immune
responses of homogametic persons against heterogametic
subjects of the same species, which are otherwise genetically
identical. Such responses have been shown in mammals,
birds, and amphibians.
H-Y system
Genes on the Y chromosome encode H-Y antigens that
are “self” when expressed in males amd “non-self” when
expressed in females who are otherwise genetically
identical.