Binding, internalization and degradation of soluble aggregates of human secretory IgA by resident rat peritoneal macrophages

Immunology. 1988 Aug;64(4):703-8.

Abstract

In the present study the in vitro binding, internalization and degradation of IgA immune complexes (IC) by phagocytes was studied. As a model for IgA IC, heat-aggregated human secretory IgA (AsIgA) was prepared and resident rat peritoneal macrophages (PM phi) were used as a source of phagocytes. First, binding of 125I-AsIgA to rat PM phi was investigated. Binding of 125I-AsIgA to PM phi at 4 degrees was saturable and reached plateau values after 2 hr. At 37 degrees, degradation of membrane-bound 125I-AsIgA into trichloroacetic acid (TCA)-soluble fragments occurred. Parallel experiments with unlabelled AsIgA and 125I-labelled anti-human IgA revealed that degradation of AsIgA was preceded by internalization of AsIgA. The specificity of binding of 125I-AsIgA to PM phi was investigated using human IgG, human serum IgA, human myeloma IgA1, human sIgA and the glycoproteins asialofetuin and ovalbumin. The binding of 125I-AsIgA to rat PM phi was inhibited in the presence of sIgA and asialofetuin. In contrast IgG and ovalbumin had no effect. These results suggest that receptors with a specificity for galactose on the rat PM phi are involved in the binding of AsIgA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigen-Antibody Complex / metabolism*
  • Binding, Competitive
  • Hot Temperature
  • Immunoglobulin A, Secretory / immunology
  • Immunoglobulin A, Secretory / metabolism*
  • Kinetics
  • Macrophages / physiology*
  • Peritoneal Cavity / immunology
  • Phagocytosis*
  • Protein Denaturation
  • Rats
  • Rats, Inbred Strains

Substances

  • Antigen-Antibody Complex
  • Immunoglobulin A, Secretory