Mono/polyclonal free light chains as challenging biomarkers for immunological abnormalities

Area of Science:

• Clinical Immunology
• Biochemistry
• Nephrology

Background:

• Free light chains (FLCs) are proteins produced during immunoglobulin synthesis.
• FLCs are filtered by the kidneys, making serum levels indicative of plasma cell activity and renal function.
• Monoclonal (mFLC) and polyclonal (pFLC) FLCs can be detected in various body fluids.

Purpose of the Study:

• To highlight the diagnostic and monitoring utility of FLCs in different body fluids.
• To discuss the role of FLCs in plasma cell dyscrasias and inflammatory diseases.
• To explore the potential of salivary FLCs for monitoring infectious diseases like COVID-19.

Main Methods:

• Serum, urine, and cerebrospinal fluid analysis for FLCs.
• Detection of monoclonal and polyclonal FLCs.
• Review of current clinical applications and future research directions.

Main Results:

• Serum mFLC measurement is recommended for multiple myeloma diagnosis and monitoring.
• Urinary FLCs indicate renal injury, while CSF FLCs aid in diagnosing CNS inflammatory diseases.
• Elevated pFLCs are associated with B cell activation in conditions like autoimmune diseases and HCV infection.

Conclusions:

• FLCs are valuable biomarkers across various clinical settings.
• Monitoring FLCs aids in disease diagnosis, prognosis, and management.
• Further research into salivary FLCs for pandemic monitoring is warranted.