The natural mediator for PMN emigration in inflammation: IV. In vitro production of a chemotactic factor by papain from immunoglobulin G

In earlier work, a chemotactic factor (leucoegresin) specific for neutrophilic polymorphonuclear (PMN) leucocytes had been isolated from an inflamed site. The substance shared antigenic sites in common with IgG, and was produced in vitro from IgG by a purified neutral SH-dependent protease from inflammatory tissue.

A similar chemotactic factor was produced in vitro by papain from serum IgG of rabbit, mouse and man. The molecular size of the substance was approximately 140,000 when measured by gel filtration on Sephadex G-200, suggesting a minor structural change of the IgG molecule; it was indistinguishable from the molecular size of leucoegresin. Both Fab and Fc fragments from IgG showed no chemotactic activity. The chemotactic generation by the enzyme was found positive only for papain-resistant IgG; it included rabbit IgG with an electrophoretically fast mobility, human IgG₂ and IgG₄, and mouse IgG₁. Negative results were obtained with papain-sensitive IgG such as rabbit IgG with an electrophoretically slow mobility, human IgG₁ and IgG₃, and mouse IgG_2a and IgG_2b. The observations described suggest that the production of a chemotactic factor in inflammation may be associated with a structure specificity of IgG.