Alveolar type II cell (null)

Molecular Classification

Other (specialized epithelial cell)

Other Names

type II pneumocyte, type II alveolar cell, alveolar epithelial type II cell, AEII cell

Disease Roles

Respiratory distress syndrome (especially in premature infants due to surfactant deficiency)Acute respiratory distress syndrome (ARDS)Infection (notably COVID-19)

Alveolar type II cell Overview

Alveolar type II cells are specialized epithelial cells in the lung alveoli responsible for synthesizing, secreting, and recycling surfactant to reduce surface tension, maintain alveolar stability, and prevent collapse. They serve as progenitor cells capable of regenerating both type I and type II alveolar cells after injury, contribute to fluid and ion homeostasis, modulate immune responses through cytokine and growth factor secretion, and participate in lung repair and host defense. Dysfunction or immaturity of type II cells is central to conditions such as respiratory distress syndrome and acute lung injury, with clinical relevance in infectious and inflammatory pulmonary diseases.

Mechanism of Action

Glucocorticoids stimulate surfactant protein production and maturation of type II cells. Certain drugs, including SSRIs, may modulate inflammatory response or cell integrity in the context of severe infection or ARDS.

Biological Functions

Surfactant synthesis and secretion

Regulation of alveolar surface tension

Regeneration of alveolar epithelium after injury (progenitor for type I and type II cells)

Ion and water transport

Host defense, including immune modulation and cytokine secretion

Regulation of coagulation/fibrinolysis balance

Disease Associations

Respiratory distress syndrome (especially in premature infants due to surfactant deficiency)

Acute respiratory distress syndrome (ARDS)

Infection (notably COVID-19)

Lung injury repair

Safety Considerations

Dysfunction or loss leads to surfactant deficiency, alveolar collapse, impaired gas exchange, and susceptibility to lung injury.
Therapeutic manipulation may inadvertently impair repair/regeneration or host defense mechanisms.

Interacting Drugs

Glucocorticoids

SSRIs—fluvoxamine, fluoxetine

Associated Biomarkers

Biomarker
MUC1 (as a marker in some lung cancers)
Surfactant proteins (SP-A, SP-B, SP-C, SP-D)