Significance and problem of commercially available anti-humam free light chains antibodies

Sensitivity and specificity of commercial anti-human free light (L) chains antibodies (DAKO Co. and Binding Site Co.) for detection of Bence Jones protein (BJP) were compared with those of conventional anti-human L chains antibodies (DAKO Co.), and the usefulness and problems of these antibodies were investigated. When BJP positive serum and urine were used, sensitivity of anti-human free L chains antibodies against BJP was lower than that of conventional anti-human L chains antibodies in many cases. The anti-human free L chains antibodies also reacted with not only free L chains but also with intact Igs, i.e., L chains linked to H chains. Therefore, care must be taken when the antibodies are used in a specific sensitive method such as immunoblotting.