Chitinase activity in human serum and leukocytes

Area of Science:

• Immunology
• Biochemistry
• Mycology

Background:

• Chitin, a polysaccharide in fungal cell walls, is a potential target for host defense mechanisms.
• The presence and function of chitinases in human immune cells and serum were previously uncharacterized.

Purpose of the Study:

• To investigate the presence and localization of chitinase activity in human leukocytes and serum.
• To characterize the biochemical properties of human leukocyte chitinase.
• To explore the potential role of human chitinase in host defense against fungal infections.

Main Methods:

• Utilized colloidal [3H] chitin as a substrate to measure chitinolytic activity.
• Employed leukocyte fractionation to determine enzyme distribution.
• Used the specific chitinase inhibitor allosamidin to confirm enzyme specificity.
• Analyzed protein molecular masses via polyacrylamide gel electrophoresis.

Main Results:

• Demonstrated chitinase activity in human leukocytes, with significantly higher levels in granulocytes compared to lymphocytes and monocytes.
• Detected chitinase activity in human serum at lower levels.
• Showed partial inhibition of chitinolytic activity by allosamidin, confirming it as a chitinase.
• Identified proteins with chitinolytic activity (48 and 56 kDa) distinct from lysozyme in granulocytes.

Conclusions:

• Human leukocytes, particularly granulocytes, possess significant chitinase activity.
• Chitinase is present in human serum, suggesting a systemic role in host defense.
• This enzyme activity may contribute to host protection by degrading fungal cell wall chitin, thus aiding in the clearance of fungal pathogens.