**Folikel limfatik** (bahasa Inggris: *lymphoid follicle*) adalah suatu struktur pada sistem limfatik, seperti nodus limfa dan *Peyer's patch*, yang mengandung banyak sel B. Area folikel terdiri dari:

* area folikel primer, tempat penyimpanan dan pembibitan sel B
* area folikel sekunder, tempat sel B yang telah matang oleh pusat germinal

Folikel limfoid adalah struktur yang menarik dan telah mendapat banyak perhatian dari banyak patologis. Hal yang menarik tersebut adalah kompleksitas lingkungan mikro yang terdiri atas sel-sel imun, molekul adhesi, sitokin, dan kompleks antigen-antibodi, serta hubungan antara komponen-komponen ini dalam produksi antibodi dengan afinitas tinggi dan pembentukan sel B memori.

Mekanisme transport antigen
---------------------------

Tew dan kawan-kawan telah melaporkan secara ekstensif mekanisme yang terlibat dalam jalur transportasi antigen yang mengarah ke pusat reaksi germinal. Jalur ini merupakan alternatif untuk menjebak dan mengolah antigen oleh makrofag dan disebut jalur antigen alternatif. Secara singkat, kompleks antigen-antibodi ditemukan dalam makrofag sinusoidal dan pada permukaan sel dendritik sinusoidal segera setelah pengenalan antigen. Antigen dikirim ke sel dendritik folikular oleh pergerakan baik antigen maupun sel dendritik sinusoidal ke pusat folikel. Pada hari 3 setelah pengenalan antigen, antigen ditemukan pada permukaan sel dendritik folikular sebagai badan dilapisi kompleks imun, juga disebut ikososom. Antigen kemudian dilepaskan oleh sel dendritik folikular dan diambil oleh sel-sel B folikel dengan antigen ditemukan di vesikel seperti lisozim pada hari 5. Antigen diproses oleh sel B (seperti yang ditunjukkan oleh studi horseradish peroksidase dengan produk HRP ditemukan terkait dengan aparatus Golgi) dan ditransfer ke permukaan sitoplasma. Sel B menyajikan antigen untuk sel T dengan mediasi dari berbagai sitokin termasuk IL-2, IL-4, IL-5, IL-6, dan interferon-γ, dan terjadilah aktivasi, proliferasi, dan diferensiasi sel B. Hasil akhirnya adalah produksi sel B memori dan sel yang memproduksi antibodi (sel plasma) dalam menanggapi antigen tertentu. Sel-sel dendritik folikular memainkan peran integral di pusat reaksi germinal.

Referensi
---------

1. ↑  (Inggris) "Immunobiology, glossary, follicles". *Charles A. Janeway, et al*. Diarsipkan dari versi asli tanggal 2023-07-22. Diakses tanggal 2010-03-20.
2. ↑  (Inggris) "Immunology, glossary, primary follicles". *Charles A. Janeway, et al*. Diarsipkan dari versi asli tanggal 2023-07-22. Diakses tanggal 2010-03-20.
3. ↑  Tew JG, Wu J, Qin D, Helm S, Burton GF, Szakal AK (1997). "Follicular dendritic cells and presentation of antigen and costimulatory signals to B cells". *Immunol Rev*. **156**: 39–52. PMID 9176698.
4. ↑  Tew JG, Kosco MH, Szakal AK (1989). "The alternative antigen pathway". *Immunol Today*. **10** (7): 229–32. PMID 2679634.

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Darah |
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| Cairan tubuh |
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| Serum | 

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| Globulin |
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| Alfa | 
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| Beta | 
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| Gamma | Antibodi |

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| Regulator | Hormon |
| Lipida | 
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| Klot | I "II "III "IV "V "VII "VIII "IX "X "XI "XII "XIII "Keping darah "Trombus "Protein C "Protein S |
| Sel | 

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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Darah | 

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| Merah |
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| Putih |
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| Limfosit | 

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| Sel T | 

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| Pembantu | 

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| Sel TH1 | IL-2  **·**  TNF-ß  **·**  IFN-γ |
| Sel TH2 | IL-4  **·**  IL-5  **·**  IL-13 |

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| Sel NK | IL-4 "IFN-γ |
| Sel NKT | 
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| Sel T γδ | 
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| Memori | 

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| Sel T CM | 
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| Sel T SCM | 
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| Sel T EM | 
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| Sel T EMRA | 
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| CD8 | 
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| CD4 | 
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CRH -GC |
| Sel B | 

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| Sel B-1 | 
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| Sel B-2 | 
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| Plasmablas | Sel plasma |

 **·**  IgG |

Limfoblas  **·**  LAK "PIT |
| Granulosit | 

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| --- | --- |
| Basofil | 
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| Eosinofil |  **·**  Deoksiribonuklease  **·**  Eosinofil peroksidase  **·**  Histamin  **·**  Lipase  **·**  Plasminogen  **·**  Ribonuklease |
| Neutrofil | 

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| Mielosit | 
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| Metamielosit | 
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| Neutrofil band | 
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| Neutrofil segmen | 
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| Monosit | 

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| --- | --- | --- | --- | --- | --- |
| Makrofaga | 

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| Normal | Histiosit "Sel Kupffer "Alveolar "Pleural "Peritoneal "Langerhans's cell |
| Radang | 
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| DC | 

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| Mieloid | 
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| Plasmasitoid | 
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| Sel DC AP | IL-12 |
| FDC | 
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 **·**  Langerin |

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| Endosit | 

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| --- | --- | --- | --- | --- | --- |
| Fagosit | 

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| Pro | Makrofaga "Neutrofil "Sel biang: Heparin  **·**  Histamin  **·**  Sitokina |
| Nonpro | Eritrosit "Fibroblas "Limfosit "Sel endotelial "Sel epitelial |

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| Pinositosit | DC |

Sel M |

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| Punca | Mesenchimal "Progenitor |
| Endotelial | 
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| Epitelial | 
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| Hati | Hepatosit "Ito |

Astrocit: Demosterol  **·**  Kolesterol  **·**  Latosterol  **·**  Vesikel |

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| Lihat pula: Asam amino "Hormon "Enzim |