Chondro/osteoclasts and mast cells are co-villains in the joint destruction of rheumatoid arthritis

Chondro/osteoclasts and mast cells are cells of interest in the cartilage and bone destruction of joints affected by rheumatoid arthritis (RA). Both are major cellular components of the vascular synovial pannus proliferation characteristic of this disease. Chondroclasts degrade calcified cartilage and osteoclasts degrade bone tissue. Chondroclasts and osteoclasts are identical cell types and differentiate from monocyte precursors. Our studies show a close microanatomical relationship between these cells and new capillary formation (shown by the lectin Psophocarpus tetragonolobus - PTL-11) in the resorption sites of the mineralized tissues. Clast and mast cells express receptors for the lectin lPHA indicating beta1,6-acetylglucosaminal transferase V (GNTase V/MGAT5) activity providing a mechanism for neoangiogenesis. In addition to an angiogenetic function for mast cells it is probable that their products control monocyte differentiation and chondro/osteoclastogenesis.