What distinguishes endotoxins from exotoxins?

The distinguishing factor between endotoxins and exotoxins lies in their origin and structure. Endotoxins are components of the outer membrane of the cell wall of Gram-negative bacteria, specifically lipopolysaccharides (LPS). They are not secreted but are released when the bacterial cell is lysed.

In contrast, exotoxins are typically secreted by both Gram-positive and Gram-negative bacteria as proteins that can interact with host cells and cause damage or disrupt cellular function. This fundamental difference in their nature—where one is part of the bacterial structure (endotoxin) and the other is actively produced and released (exotoxin)—clearly defines their classifications.

Awareness of these distinctions is crucial, especially in understanding the pathogenicity and immunological responses associated with various bacterial infections.