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Molecular and Cellular Pediatrics
Fig. 2 | Molecular and Cellular Pediatrics

Fig. 2

From: Autoimmune lymphoproliferative immunodeficiencies (ALPID) in childhood: breakdown of immune homeostasis and immune dysregulation

Fig. 2

The two-step process of T cell activation. To counteract it, CTLA-4 in endosomes reaches the cell surface, outcompetes CD28, and binds and downregulates CD80/CD86 in a process called trogocytosis. LRBA acts intracellularly to stabilize and protect intracellular CTLA-4 from lysosomal degradation, thus maintaining the pool of available CTLA-4. Both in CTLA-4 haploinsufficiency and LRBA deficiency, lack of CTLA-4 (either due to decreased translation or increased lysosomal degradation) limits the function of regulatory T cells. Abatacept is a soluble CTLA-4 immunoglobulin fusion protein (Fc-region of human IgG1 linked to the extracellular domain of CTLA-4), which mimics CTLA-4 function and can be used successfully as a targeted therapy in both conditions

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