A naturally occurring complement dependent human IgM macroglobulin inhibitory to Ehrlich ascites tumor cells

Area of Science:

• Immunology
• Cell Biology
• Biochemistry

Background:

• Mammalian sera possess naturally occurring macroglobulins with antibody-like functions.
• These macroglobulins exhibit complement-dependent cytotoxicity against specific tumor cells.
• Ehrlich ascites tumor cells are susceptible to this cytotoxic activity in vitro.

Purpose of the Study:

• To investigate the cytotoxic properties of human and mammalian serum macroglobulins.
• To characterize the mechanism of cytotoxicity against murine Ehrlich ascites tumor cells.
• To determine the role of complement in mediating this cytotoxic effect.

Main Methods:

• Short-term tissue culture of murine Ehrlich ascites tumor cells.
• Assay of cytotoxic activity in human and various mammalian sera.
• Measurement of nucleic acid and protein synthesis inhibition.
• Assessment of complement's role in cytotoxicity.

Main Results:

• Human and some mammalian sera contain a macroglobulin cytotoxic to Ehrlich ascites tumor cells in vitro.
• Complement is required for the observed cytotoxic activity.
• Cytotoxicity is characterized by immediate inhibition of nucleic acid and protein synthesis.
• The cytotoxic activity is distinct from antibody systems targeting neuraminidase-treated lymphocytes.

Conclusions:

• A naturally occurring macroglobulin in human serum exhibits complement-dependent cytotoxicity against Ehrlich ascites tumor cells.
• This macroglobulin effectively inhibits essential cellular processes like nucleic acid and protein synthesis.
• The findings suggest a potential role for such macroglobulins in tumor cell control and warrant further investigation.