Ultrastructural evidence for colocalization of kappa light chain- and beta 2-microglobulin-derived amyloids using double labelling immunogold electron microscopy.

In systemic amyloidosis, it is essential to decide what type of amyloid protein is deposited in tissues before the therapy can be selected and the prognosis assessed in each patient. We examined tissues affected by amyloid deposition from a patient with multiple myeloma by immunohistochemistry and double labelling immunogold electron microscopy and demonstrated colocalization of kappa light chain- and beta 2-microglobulin-derived amyloids in the same tissue. beta 2-Microglobulin-derived amyloid had ultrastructurally characteristic features that distinguished it from kappa light chain-derived amyloid. This is the first report of the colocalization of two different amyloids by immunoelectron microscopy.