In addition to ingesting small microorganisms such as bacteria by phagocytosis, neutrophils and eosinophils can assist in the elimination of larger invaders by trapping them within webs called neutrophil extracellular traps or NETs (Figure 1). The strands for these NETs are composed of polynucleotide strands generated by the dispersal, or decondensation, of a neutrophil’s chromosomal DNA. This process involves rupture of the nuclear membrane and the disruption of the favorable charge–charge interactions that normally stabilize chromatin. Dissolution of histone-polynucleotide complexes is promoted by the enzyme peptidylarginine deiminase, which catalyzes the deimination of the strongly basic side chains of arginine residues to form neutral citrulline residues (Figure 2). Some chromatin proteins do remain associated with the DNA, forming cross-links between the polynucleotide strands. Granule membranes also rupture at this time, releasing their contents into the cytoplasm where they can bind to the decondensing polynucleotide strands, decorating the DNA with granule-derived proteases, antimicrobial peptides, and other factors. Eventually, the neutrophils lyse, unleashing their NETs on invading parasites in order to immobilize them and hinder their spread.

Fig1. Trapping parasites using NETs. The figure depicts the basic stages in the formation and deployment of a DNA-based web by a neutrophil or eosinophil to trap a parasitic microorganism. (A) Resting neutrophil. The multilobed nucleus is shown in hatched purple, intracellular granules in green, and granule enzymes and cytotoxins as orange circles and yellow triangles. (B) On stimulation, the membranes encasing the nucleus and granules rupture, releasing enzymes, cytotoxins, and strands of DNA (purple) from decondensing chromosomes.(C)The DNA strands form a mesh that fills the interior of the cell to which some granule-derived proteins adhere. (D)The neutrophil lyses, releasing its DNA-protein web, which entraps the parasite (orange) against surface of the epithelium (hatched).

Fig2. Citrullination. The enzyme peptidyl arginine deiminase displaces one of the imino groups (red) on the side chain of arginine by an oxygen atom (blue) derived from water. The net result is to replace a positive charge provided by the protonated arginine side chain by an amide, which is neutral.

اخر الاخبار

اخبار العتبة العباسية المقدسة

قسم الهدايا والنذور يباشر خياطة أوشحة المشاركات في حفل سن التكليف الشرعي

مؤسسة القبس: العتبة العباسية المقدسة تسهم في خدمة المجتمع بمختلف المجالات عبر مشاريعها المتنوعة

قسم الشؤون الفكرية يعرض منجزات مراكزه المتخصصة في حفظ التراث المخطوط ضمن فعاليات مهرجان عين الحياة

في مقابلة خاصة.. مديرة مكتب المتولي الشرعي للشؤون النسوية توضح أهداف حفل التكليف الشرعي وأبعاده التربوية

المزيد

الآخبار الصحية

الشاي والقهوة وتدهور الذاكرة.. دراسة تكشف نتائج جديدة

هل يساعد الزنك على تحسين النوم والطاقة؟

علامات يجب عدم تجاهلها بعد تناول مكملات "فيتامين د"

لتجنب ارتفاع سكر الدم.. ما أفضل وقت لتناول الحلوى؟

المزيد

الآخبار التكنلوجية

الإمارات ترسخ مكانتها كأحد أبرز قادة الذكاء الاصطناعي عالميا !

"أوبن إيه آي" تحذر المشرعين الأميركيين من تحايل "ديب سيك" ؟

تصاعد التوتر بين "أبل" وإدارة ترامب.. ما السبب؟

سلاح طبي في ساحات الحرب.. رذاذ يوقف النزيف خلال ثانية !

المزيد

مواضيع ذات صلة

Immunotherapy

Immune Tolerance and Autoimmunity

Cellular interactions in regulation of normal immune responses

Markers of Granulocytic Maturation

The Complement System Also Protects Against Infection

Monocytopoiesis

Eosinophil Production

Transcription Factors Regulating Myeloid Differentiation and Myeloid-Specific Gene Expression

Cytokine Regulation of Myeloid Proliferation and Differentiation

Neutrophil Granules and Their Content Proteins

Stages of Neutrophil Differentiation

T Lymphocytes, Transfer of Safety Genes, and Strategies to Improve Tumor Cell Specificity