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The Collaborative International Dictionary of English v.0.48 (gcide)

anaphylaxis \an`a*phy*lax"is\ n.
([a^]n`[.a]*f[imac]*l[a^]k"s[i^]s or
[a^]n`[.a]*f[i^]*l[a^]k"s[i^]s)
1. [Gr. 'ana` back, way from fy`laxis security,
protection.]

1. (Med.) Hypersensitivity (to a foreign antigen) resulting
from prior contact with the same or a related substance.
[WordNet 1.5 AS]

2. (Med.) An immediate but transient systemic reaction to an
antigenic substance to which a person has become
hypersensitized; it is characterized by the contraction of
smooth muscle and capillary dilation. --[Stedman]
[PJC AS]

Note: The cascade of events is triggered by binding of the
foreign antigen to immunoglobulin E and release of
mediators such as histamine, bradykinin, serotonin, and
slow-reacting substance from mast cells. It involves
more than one organ system. The most commonly involved
organs are skin, cardiovascular, respiratory and
gastrointestinal systems. Anaphylaxis is manifested by
a range of signs and symptoms including pruritus,
urticaria, itching, dyspnea, abdominal pain and
cardiovascular collapse (shock). A severe form of the
reaction is called {anaphylactic shock}. --[Stedman]
[PJC AS]

3. (Med) Anaphylactic shock.
[AS]


anaphylactic shock \anaphylactic shock\ n.
([a^]n`[.a]*f[imac]*l[a^]k"t[i^]k sh[o^]k`) (Med.)
Shock resulting from anaphylaxis[2]. It is a severe form of
physiological shock, often having a fatal outcome, and is
caused by an extreme immunological reaction to antigens. It
is characterized by smooth muscle contraction and capillary
dilation throughout the body, initiated by antibodies of the
IgE class. It is usually seen when an antigen to which a
person has become hypersensitized is injected intravenously
or subcutaneously. It is also called {generalyzed
anaphylaxis} or {systemic anaphylaxis}, and sometimes
{anaphylaxis}. --[Stedman]
[PJC AS]