Lymphokine and phorbol (PMA) regulation of complement (C2) synthesis using U937

Area of Science:

• Immunology
• Complement System Biology

Background:

• Human monocytes produce complement component C2.
• Monocyte complement stimulator (MCS) from T-lymphocytes enhances C2 synthesis.
• The U937 cell line mimics monocyte behavior.

Purpose of the Study:

• Investigate U937 cells' C2 synthesis.
• Determine factors stimulating C2 production in U937 cells.
• Analyze the mechanism of C2 stimulation.

Main Methods:

• Incubation of U937 cells with lymphokine-rich supernates and PMA.
• Measurement of C2 synthesis.
• Assessment of [3H]thymidine incorporation.
• Inhibition studies with cycloheximide.

Main Results:

• U937 cells synthesize C2.
• Lymphokines and PMA significantly increase C2 synthesis by U937 cells.
• PMA-induced C2 synthesis is not due to increased cell proliferation.
• Stimulation by lymphokines and PMA is reversibly inhibited by cycloheximide.

Conclusions:

• U937 cells are a useful model for studying C2 synthesis.
• Lymphokines and PMA are potent stimulators of C2 production in monocytes/macrophages.
• The regulation of C2 synthesis involves protein synthesis and is sensitive to cycloheximide.