Free Immunoglobulin Light Chain

**Semantic type:** Amino Acid, Peptide, or Protein

**Definition:** Immunoglobulin kappa and/or lambda light chains that are not bound to immunoglobulin heavy chains. These proteins are produced in vivo by B-cells but can be synthesized ex vivo for use as diagnostic or therapeutic agents.

**Synonyms:** - FLK - Free Light Chain