T cells are born from hematopoietic stem cells,[1] found in the bone marrow. Developing T cells then migrate to the thymus gland to develop (or mature). T cells derive their name from the thymus.[2][3] After migration to the thymus, the precursor cells mature into several distinct types of T cells. T cell differentiation also continues after they have left the thymus. Groups of specific, differentiated T cell subtypes have a variety of important functions in controlling and shaping the immune response.
One of these functions is immune-mediated cell death, and it is carried out by two major subtypes: CD8+ “killer” (cytotoxic) and CD4+ “helper” T cells. (These are named for the presence of the cell surface proteins CD8 or CD4.) CD8+ T cells, also known as “killer T cells”, are cytotoxic – this means that they are able to directly kill virus-infected cells, as well as cancer cells. CD8+ T cells are also able to use small signalling proteins, known as cytokines, to recruit other types of cells when mounting an immune response. A different population of T cells, the CD4+ T cells, function as “helper cells”. Unlike CD8+ killer T cells, the CD4+ helper T (TH) cells function by further activating memory B cells and cytotoxic T cells, which leads to a larger immune response. The specific adaptive immune response regulated by the TH cell depends on its subtype (such as T-helper1, T-helper2, T-helper17, regulatory T-cell),[4] which is distinguished by the types of cytokines they secrete.[2]
Regulatory T cells are yet another distinct population of T cells that provide the critical mechanism of tolerance, whereby immune cells are able to distinguish invading cells from “self”. This prevents immune cells from inappropriately reacting against one’s own cells, known as an “autoimmune” response. For this reason, these regulatory T cells have also been called “suppressor” T cells. These same regulatory T cells can also be co-opted by cancer cells to prevent the recognition of, and an immune response against, tumor cells.
「“免疫” 曖昧な“わたし”をめぐるドラマ」
ヒューマニエンス ４０億年のたくらみ
NHK
https://www.nhk-ondemand.jp/goods/G2023130126SA000/
わたしたちを２４時間守り続ける「免疫」。その心強い味方を邪魔する“Ｔレグ”という細胞が今回の主役だ。なぜ免疫なのに免疫の攻撃を邪魔するのか。実は“わたし”という存在をあえて曖昧にとらえるため、５億年前わざわざ発明されたことがわかってきた。さらに免疫システムに自ら攻撃を停止する“疲弊”スイッチも明らかに。ヒト誕生から老化まで、免疫システムの働きを今回は学園ドラマ化して再現。その奥深い世界を妄想する。
①自然免疫（バクバク食べる）
②獲得免疫（T細胞を代表とするもの）
獲得免疫は胸腺で作られる：胸腺はT細胞を作るためだけの臓器で、幼児期から思春期まで機能し、次第に退縮する。
「T細胞候補生」がたんぱく質を作るための全ての遺伝子を学ぶ。（18,000種）最終的に残るのは全体の1割。
T細胞は三つに分類される（T3） T：Thymus（胸腺）
①ヘルパーT 司令官
②キラーT 実行部隊
③Tレグ これが特殊
異物が入り込んでくる
樹状細胞が検知し報告する
→ヘルパーTが照合しキラーTに指令
→パーフォリン（細胞を溶かすたんぱく質）で排除
T細胞の受容体の種類は1000億個
→「こういう病原体」という特定が難しい。
適当に作る（適当が大事）
パーフォリンは自殺を促すもの
（積極的な攻撃ではない）
樹状細胞が異物らしきものを見つけてヘルパーTに通報しようとする
→それを止めて対応したのがTレグ。
→実は異物ではなかったのだ（Tレグには識別ができた）。
ヘルパーT、キラーTで9割を占め、Tレグは1割しかない。
赤ちゃんの半分は異物（父親の遺伝子）なぜ攻撃が起きないか。
受精卵が子宮に向かう時、免疫反応の攻撃から守るのがTレグ。
着床するまでの間Tレグは通常の3.5倍分泌される。
2回目に同じ父の精子を受け入れる時は妊娠し易い。
（免疫の記憶）
ヒューマニエンス「“免疫” 曖昧な“わたし”をめぐるドラマ」
https://ameblo.jp/yashima1505/image-12821009244-15339799498.html
T cell
Wikipedia
https://en.wikipedia.org/wiki/T_cell
T cells are born from hematopoietic stem cells,[1] found in the bone marrow. Developing T cells then migrate to the thymus gland to develop (or mature). T cells derive their name from the thymus.[2][3] After migration to the thymus, the precursor cells mature into several distinct types of T cells. T cell differentiation also continues after they have left the thymus. Groups of specific, differentiated T cell subtypes have a variety of important functions in controlling and shaping the immune response.
One of these functions is immune-mediated cell death, and it is carried out by two major subtypes: CD8+ “killer” (cytotoxic) and CD4+ “helper” T cells. (These are named for the presence of the cell surface proteins CD8 or CD4.) CD8+ T cells, also known as “killer T cells”, are cytotoxic – this means that they are able to directly kill virus-infected cells, as well as cancer cells. CD8+ T cells are also able to use small signalling proteins, known as cytokines, to recruit other types of cells when mounting an immune response. A different population of T cells, the CD4+ T cells, function as “helper cells”. Unlike CD8+ killer T cells, the CD4+ helper T (TH) cells function by further activating memory B cells and cytotoxic T cells, which leads to a larger immune response. The specific adaptive immune response regulated by the TH cell depends on its subtype (such as T-helper1, T-helper2, T-helper17, regulatory T-cell),[4] which is distinguished by the types of cytokines they secrete.[2]
Regulatory T cells are yet another distinct population of T cells that provide the critical mechanism of tolerance, whereby immune cells are able to distinguish invading cells from “self”. This prevents immune cells from inappropriately reacting against one’s own cells, known as an “autoimmune” response. For this reason, these regulatory T cells have also been called “suppressor” T cells. These same regulatory T cells can also be co-opted by cancer cells to prevent the recognition of, and an immune response against, tumor cells.
T cell
Happy thanksgiving!
How thankful am I to you and
Grateful for your protection
Together till death
My body die and you too
My T cell