Skip to main content



Ag = Antigen
Ab= Antibody

Ag-Ab complexes are formed in this disorder which deposits in various tissues and induce inflammation in them and gradually destroys them.
Ag-Ab complexes formation is a normal phenomenon in most of the situations but they do not deposit normally. It is the size of the complexes or the functional or structural abnormality of the mononuclear phagocytic cells which render the Ag-Ab complexes to be deposited in various locations. Charge and three-dimensional structure of the immune complexes, the valency of the Ag, the affinity of the Ag to various tissue components and hemodynamic factors also play roles in the deposition of the complexes.


Type III hypersensitivity diseases may be systemic or local. In both of them the pathogenesis is divided into three phases:
•The first phase (formation of Ag-Ab complexes): In this Ag enters the body interacts with the immunocompetent cell which produces Abs against that Ag. This process takes about one week. The Abs react with the Ag in circulation and form Ag-Ab complexes.
•The second phase (Deposition of circulating complexes): In this phase the circulating complexes deposit in various tissues.
•The third phase (acute inflammatory reaction): in this phase acute inflammatory reaction is initiated by activation of the complement cascade which in response activate neutrophils and monocytes
type 3 hypersensitivity Image
through their Fc receptors. This phase is represented by fever, urticaria, arthralgias, lymph nodes enlargement and proteinuria.

•Antigen/Antibody “Complexes” mainly deposit in the:

–Kidney (Glomerular Basement Membrane)
–Blood Vessels, Skin and Joints

Common Type III Diseases:-

Systemic Diseases:

SLE, Polyarteritis nodosa, Post-streptococcal glomerulonephritis, Serum sickness (days).

Local diseases:

Arthus reaction
Read also:

1. Type One Hypersensitivity Reaction-Causes-Types-Phases-Mediators And Examples Of Type One Hypersensitivity Reaction

Type 2 ( Antibody Mediated ) Hypersensitivity Reaction-Mechanism-Diseases And Examples

Vist Home Page


Popular posts from this blog

Human Parasites, Types of Parasites, and Classification

Parasite: A parasite is a living organism which gets nutrition and protection from another organism where it lives. Parasites enter into the human body through mouth, skin and genitalia. In this article, we will generally discuss the types and classification of parasites. It is important from an academic point of view. Those parasites are harmful, which derives their nutrition and other benefits from the host and host get nothing in return but suffers from some injury. Types of Parasites Ecto-parasite: An ectoparasite lives outside on the surface of the body of the host. Endo-parasite: An endo-parasite lives inside the body of the host, it lives in the blood, tissues, body cavities, digestive tract or other organs. Temporary parasite: A temporary parasite visits its host for a short period of time. Permanent parasite: Permanent parasite lives its whole life in the host. Facultative parasite: A facultative parasite can live both independently and dependently. It lives in the

How to taper off, wean off beta blocker, atenolol, Propranolol, Metoprolol

Beta blockers include, atenolol (Tenormin), propranolol (Inderal ) and metoprolol (Lopressor) and are used to treat high blood pressure, certain cardiac problems, migraine and few other conditions. People usually take atenolol, propranolol or metoprolol for many years as a treatment of high blood pressure or after having an episode of heart attack . Sometimes, it becomes necessary to withdraw these beta blockers due to their potential side effects that trouble the patients or sometimes doctor wants to change the drug and shift the patient to some other anti-hypertensive medicine. No matter whatever the cause is, whenever, a patient who has been using a beta blocker for a long period of time, and he needs to be stopped from further usage of that beta blocker, must not stop taking it. One should taper off the dose of a beta blocker. Now a question arises how to wean off or taper off a beta blocker? The method of tapering off beta blocker varies from individual to individual. Allow you