|Dust, feathers,Pollen, foodstuffs,
|Anaphylactic antibodies of class
|Cell membrane fragments or antigens
(haptens) deposited on cell Cell
|Cytotoxic antibodies of classes IgG ,IgM,IgA|
|Foreign serum drugs, antigens
from streptococci and tumors
|Precipitating antibodies of class
IgG plus complement
|Cell-mediated defense ( Type IV )
|Chemicals and noxious substances
of different kinds
|Reaction Mechanism||Effects||Clinical manifestation|
|The reaction of IgE with the antigens
causes degranulation of the mast cells,
followed by release of histamine
serotonin, bradykinin and SRS-A
increase of vascular
contraction of smooth muscle
|Cellular antigens react with circulating
antibodies, or cellular antibodies react
with circulating antigens. Complement
becomes attached to the antigen-antibody
complex, leading to lysis of the target cell.
hemolytic anemia, autoimmune
|Deposition of antigen-antibody
Complexes in capillary walls.
Activation Of the complement system.
Leukotaxis And phagocytosis of the
immune Complexes by the leukocytes.
Lysis of The phagocytosing cells and
destruction Of the cell walls by
serum sickness ,
drug rash toxic
|As a result of the lymphocyte-antigen
reaction humoral factors ( lymphokines )
are released Allergens invade the
epidermis (contact Dermatitis) Allergens
invade the dermis (tuberculin Type )
monolympho cytic infiltration
allergic Exanthems,id reactions,
In epidermal hypersensitivity reactions, the irritants directly the affect epidermis
|Irritant and allergic
|Direct injury to skin caused by toxic chemicals
(irritant contact dermatitis) or by substances which,
though not primarily toxic, affect persons
previously sensitized to the contact allergen.
|Intertrigo||Toxic injury to skin caused by sweat and metabolic
Products of saprophytic bacteria.
|sunburns||Skin damage caused by exposure to sun light|
|phototoxic and photo-allergic
|Skin damage caused by psoralen (furocoumarin),
and other photoxic or photo-allergic agents and
subsequent exposure to sunlight .
|Nummular (bacterial ) dermatities||Skin damage due to bacterial antigens or bacterial toxins|
|Seborrheic dermatitis||Skin damage due to quantitative and qualitative
changes in sebum and sweat secretion.
|Atopic dermatitis||Skin damage due to constitutional factors
( chronic abnormal vegetative response).
In this type of hypersensitivity reaction the irritant Irritant affects both the cutis and the blood vessels.
|Edematization of the subcutaneous tissue due to
tissue due to allergic antigen –antibody reaction,
mechanical irritation or toxic factors.
|Anaphylactic shock||Massive disturbance of circulatory function due to
generalized anaphylactic hypersensitivity reaction
Of the immediate type ( Type ) .
|Erythema multiforme||Reaction of diverse etiology which may be caused
by bacterial or viral antigens or be drug-induced.
Results in edematious saturation of the tissue and
|Toxic and allergic Exanthems||Vascular hypersensitivity reaction caused by
action of various toxic or allergenic substance
( especially drugs ) ; commonly manifests as a
polymorphic eruption .
|An allergic-hyperergic reaction of the small
vessels of the dermis associated with drug
therapy or streptogenic infections .