<prompt> Macrophage chemotactic factor is -High molecular weightChymotrypsin sensitiveHeat labileAre antigenically similar to C3  <response>: Ans is b i.e.,Chymotrypsin sensitive Ref Immunology p. 278Macrophage chemotactic factor propeies has Low molecular weight 12000, has a isoelectric points of 10.1 5.6, and is sensitive to treatment by chymotrypsin while resistant to RNase and neuraminidase.It is heat stable and angenically different from C3 C5. 