Immunity and Diseases: Analysis of Complement System Disorders

This essay delves into the intricacies of immunity and diseases, focusing on the complement system. It begins by defining the complement system and its crucial role in defending the body against infections, highlighting its thirty proteins found in blood tissues and organs. The essay explains how the complement system removes microbes, damaged cells, protects against infection, and modulates adaptive immune responses. It then explores complement deficiencies, specifically primary immunodeficiency disorders, and the impact of insufficient serum proteins. The essay provides a case study of C1 esterase inhibitor deficiency, detailing its clinical features, triggers, and the role of the C1 esterase inhibitor in regulating the classical pathway of the complement system. It further explains the classical pathway, including the formation of the antigen-antibody complex, the activation of C1, and the subsequent steps involving C3 convertase and the release of vasoactive mediators.

IMMUNITY AND DISEASES 1
Immunity and Diseases
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IMMUNITY AND DISEASES 2
Immunity and Diseases
The term complement refers to the groups of serum found in the human system. These
groups of serum proteins are crucial in the body system as they defend the body against any
infection (Rother, and Till, 2012). The complement system involves thirty proteins which are
found in blood tissues and in other organs in the human cells. The main functions of the
complement systems include removing microbes and damaged cells from the body, protecting
the body from infection and helping the body by modulating the adaptive immune responses.
Upon attack of microbes, the complement systems are activated and regulate it by killing only
the invading microbes while producing collateral damage that may lead to the destruction of
human tissues (Parham, 2014).
Insufficient or deficiency of these serum proteins in the blood means that the body can
easily be attacked by infection as there. Patients with complement deficiencies are faced with
health issues that depend on the functions of this group of proteins. The deficiency of the
complement in the body system leads to a condition referred to as primary immunodeficiency
disorder. This lack of this complement system can either be inherited or complete or partial
acquired which can result in illness by promoting inflammation. The condition promotes
complement deficiency disorders a good example being C1 esterase inhibitor deficiency (Ross,
2014).
C1 esterase inhibitor defines the condition of lower levels of C1 esterase inhibitor thereby
becoming poorly functional in the human defense system. The condition mostly presents after
the second decade of human life and is mostly associated with lymph proliferative and
autoimmune diseases. The condition, also referred to as hereditary angioedema leads to episodes
of angioedema in subcutaneous tissues, gastrointestinal tract and in the upper respiratory system.

IMMUNITY AND DISEASES 3
The condition may be activated by several factors like dental extraction, stigma surgeon etc. For
instance, as in the case study of Angela, the doctors found that her condition had worsened after
dental extraction where her lips and tongue had swelling which indicates that her dental
extraction triggered the condition to worsen.
The use of estrogen which contains contraceptives and ACE- inhibitors has been shown by
several studies that it triggers acute episodes of angioedema (Abbas, Lichtman and Pillai,
2015).The clinical features of individuals associated with c1 inhibitor esterase deficiency include
swelling of external body parts like hands, faces and genital areas which lasts for about seven
days if not treated. The swelling may occur in internal organs thereby causing severe pain and
sometimes faintness or diarrhea and vomiting may occur as a result of pain generated in the
internal organs. Other symptoms may include abdominal pain, persisted coughing and
respiratory distress (Bellanti, 2013). As in the case of Angela, her tongue and lips had swollen,
had abdominal pain vomiting and laryngeal swelling which are exactly clinical features of c1
inhibitor esterase deficiency.
The c1 esterase inhibitor assumes a basic function in the guideline of the supplement
framework. The supplement framework includes three pathways which incorporate the classical
pathway, alternative pathway and mannose-binding lectin pathway (Bryan and Wu, 2014). The
enzyme, also known as the serpin c1 inhibitor regulates the classical pathway of the complement
system. The enzyme plays an important role as it is the only regulator of the classical pathway
thus this is why its deficiency in the complement systems leads to severe diseases as the body
systems are exposed to life-threatening attacks.

IMMUNITY AND DISEASES 4
Formation of antigen-antibody complex triggers the classical pathway (Merle et al., 2015).
When a foreign antigen enters the body, the antibody binds to it thereby inducing changes in
conformation in the region of Fc. Upon conformational changes of Fc, the antibody exposes a
binding site or region for C1 protein thereby activating the complement system. Therefore, the
antibody which in this case is C1 esterase inhibitor regulates the complement system by
activating the complement system only when bound to foreign microbes. The classical pathway
is the early step of the complement system, thus the need to be regulated.
It involves complement components which are named as C1, C2, and C4. Upon formation
of the antibody-antigen complex, the pathway is activated and binds to C1. The C1 has three
subgroups namely, C1q, C1r, and C1s. The pathway then forms C3 convertase that is C4b2a
which splits C3 into two subcomponents C3a and C3b. C3b covalently attaches itself to the
surface of foreign and phagocytize them. On the other hand, C3a which is a smaller fragment
activates the mast cells leading to the release of vasoactive mediators like histamine (Bellanti,
2013).