[M-component of serum formed by lambda-type Bence-Jones protein].

M-component in the serum composed of free light chains occurs rarely as evidenced by literature. In the investigations of the authors it was demonstrated that three M components obtained from patients with plasmocytoma were composed of free light chains type lambda. High concentration of low-molecular protein in serum was due, probably, to coexistent impairment of renal filtration. It is worth stressing that M component was a lambda-type chain which may explain the pathogenesis of renal failure caused by amyloidosis.