Many genetic deficiencies of complement proteins have been described, and these generally lead to enhanced susceptibility to infectious disease (eg, C2 deficiency frequently leads to serious pyogenic bacterial infections). Deficiency in components of the MAC greatly enhances susceptibility to neisserial infections. Deficiencies in components of the alternative pathway are also known (eg, properdin deficiency is associated with greater susceptibility to meningococcal disease). There are also deficiencies in complement regulating proteins. For example, lack of the C1 inhibitor protein leads to hereditary angioedema.

The complement system is an important host protective system. However, some bacteria have evolved mechanisms to evade complement activity. For example, they can inter fere with opsonization or obstruct the insertion of the MAC. Complement activation can also be inhibited by the presence of microbial generated proteins, such as protein A and protein C, that bind IgG Fc. Finally, they can generate enzymes that degrade complement components. Organisms that possess these inhibitory properties are usually more pathogenic.

The complement system has also evolved strategies to attack cell-free virus and the virus-infected cells. In response, viruses have developed mechanisms to dodge complement attack. Some viruses, such as the smallpox virus, encode proteins that can inhibit host complement function. Other enveloped viruses, such as cytomegalovirus, can pick up some of the complement regulatory proteins as they mature by bud ding from the infected cell. These regulatory proteins (CD46, CD55, and CD59) on the virus envelope can downregulate complement activation. Finally, several viruses (Epstein-Barr virus [EBV], measles virus) use complement receptors to enter and infect cells.

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شعبة الحرم الشريف تجري حملة لإدامة المرايا والثريات بمرقد أبي الفضل العباس (عليه السلام)

قسم الشؤون الفكرية ينظّم دورة متخصصة في الفهرسة الحديثة لملاكات جامعة كركوك

المجمع العلمي يواصل برنامج أشبال العميد لإحياء ليالي شهر المحرم في المثنى

المزيد

الآخبار الصحية

دراسة: البيض بريء من تهمة الكوليسترول الضار

ليست مجرد حلوى.. 7 فوائد "مذهلة" للشوكولاتة الداكنة

طفل واجه الموت.. مغناطيسان يجذبان بعضهما داخل معدته !

تعاني من الأرق؟.. إليك تمارين ستساعدك على النوم

المزيد

الآخبار التكنلوجية

أقصر يوم في تاريخ البشرية.. الموعد قريب ؟!!

مايكروسوفت تحذر شركات وأجهزة حكومية من هجوم "يوم الصفر"

لأول مرة.. فيديو يرصد ولادة كوكب !

"إكس 59".. ماذا نعرف عن طائرة ناسا "الخارقة"؟

المزيد

مواضيع ذات صلة

Cytokines

Complement Pathways

T Cells

Antibody Responses

Immunoglobulin Genes and Generation of Diversity

Immunoglobulin Classes

Immunofluorescence

Chemiluminescence

Enzyme Immunoassay

Capillary Electrophoresis

Antibody Structure and Function

B Cell Receptor for Antigen