Transmission electron microscopic studies on articular calcium crystals and associated protein coatings.

Calcium pyrophosphate (CPPD) and apatite crystals are associated with several types of arthritis. Using transmission electron microscopy both the tiny apatite-like crystals and larger CPPD can be seen to be associated with granular materials. With the ferritin bridge technique immunoglobulins and complement are seen in the material with the apatite but not the CPPD. Immunoprotein is seen both intracellularly and extracellularly. Further study of these coatings is needed to ascertain if they have consistent patterns on all crystals and how they affect the ability of the crystals to induce inflammation.