[7] They were discovered and named by Belgian biologist Christian de Duve, who eventually received the Nobel Prize in Physiology or Medicine in 1974.

[8][9] Enzymes of the lysosomes are synthesized in the rough endoplasmic reticulum and exported to the Golgi apparatus upon recruitment by a complex composed of CLN6 and CLN8 proteins.

[6][14] Mutations in the genes for these enzymes are responsible for more than 50 different human genetic disorders collectively known as lysosomal storage diseases.

Christian de Duve, at the Laboratory of Physiological Chemistry at the Catholic University of Louvain in Belgium, had been studying the mechanism of action of insulin in liver cells.

Therefore, they tried a more arduous procedure of cell fractionation, by which cellular components are separated based on their sizes using centrifugation.

[19] The same year, Alex B. Novikoff from the University of Vermont visited de Duve's laboratory, and successfully obtained the first electron micrographs of the new organelle.

Using a staining method for acid phosphatase, de Duve and Novikoff confirmed the location of the hydrolytic enzymes of lysosomes using light and electron microscopic studies.

It is thought that lysosomes participate in this dynamic membrane exchange system and are formed by a gradual maturation process from endosomes.

Lysosomal protein genes are transcribed in the nucleus in a process that is controlled by transcription factor EB (TFEB).

The presence of these tags allow for binding to mannose 6-phosphate receptors in the Golgi apparatus, a phenomenon that is crucial for proper packaging into vesicles destined for the lysosomal system.

[30] Upon leaving the Golgi apparatus, the lysosomal enzyme-filled vesicle fuses with a late endosome, a relatively acidic organelle with an approximate pH of 5.5.

[28] As the endpoint of endocytosis, the lysosome also acts as a safeguard in preventing pathogens from being able to reach the cytoplasm before being degraded.

The rate of incidence is estimated to be 1 in 5,000 births, and the true figure expected to be higher as many cases are likely to be undiagnosed or misdiagnosed.

[15] This results in abnormal signaling pathways, calcium homeostasis, lipid biosynthesis and degradation and intracellular trafficking, ultimately leading to pathogenetic disorders.

Consequently, the enzyme substrate, the fatty acid glucosylceramide accumulates, particularly in white blood cells, which in turn affects spleen, liver, kidneys, lungs, brain and bone marrow.

The disease is characterized by bruises, fatigue, anaemia, low blood platelets, osteoporosis, and enlargement of the liver and spleen.

[43] A significant part of the clinically approved drugs are lipophilic weak bases with lysosomotropic properties.

[47][48] Such compounds are termed FIASMAs (functional inhibitor of acid sphingomyelinase)[49] and include for example fluoxetine, sertraline, or amitriptyline.

[51][52] Impaired lysosome function is prominent in systemic lupus erythematosus preventing macrophages and monocytes from degrading neutrophil extracellular traps[53] and immune complexes.

[54][55][56] The failure to degrade internalized immune complexes stems from chronic mTORC2 activity, which impairs lysosome acidification.

[57] As a result, immune complexes in the lysosome recycle to the surface of macrophages causing an accumulation of nuclear antigens upstream of multiple lupus-associated pathologies.

[65] However, this is not universally accepted as the vacuoles are strictly not similar to lysosomes, such as in their specific enzymes and lack of phagocytic functions.