Ultrastructure of gamma-M immunoglobulin and alpha macroglobulin: electron-microscopic study.

Electron microscopy of purified Waldenström macroglobulins and normal human and rabbit gammaM immunoglobulins revealed spider-like structures with five legs varying in length and often joining a central ring. Usually only the central more rigid part of this structure (about 150 by 170 angstroms) was clearly visible, but occasionally particles were seen with longer very flexible legs having a total span of about 350 angstroms. Molecules of gammaM antibody retained antibody activity during preparation for electron microscopy. Human and rabbit alpha macroglobulins revealed more rigid symmetric structures (100 by 200 angstroms) which resembled the Russian letter .