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Biochemical studies on stimulation of mouse peritoneal macrophages by interaction with preformed immune complexes
A K Tripathi1, A K Chakrabarty, P S Gupta
1Department of Biochemistry and Anatomy, University College of Medical Sciences, Shahdara, Delhi, India.
Abstract:
Mouse peritoneal macrophages (MPM) were observed to be stimulated by both in vivo and in vitro interactions with preformed HSA-anti HSA immune complexes (IC) having different antigen-antibody ratios. This was indicated by cellular alterations in morphology, increase in cellular protein and lysosomal enzyme contents and a marked fall in 5' nucleotidase level. Analysis of cellular proteins of IC-elicited cells by SDS-polyacrylamide gel electrophoresis showed accumulation of 80, 47, 33, 28, 18 and 14 kDa proteins. Insoluble immune complexes at equivalence (IC-Eq) was found to be more effective in the stimulation process as compared to the soluble antigen excess complexes (IC-Ag). These IC-elicited cells secreted lesser amounts of lysosomal hydrolases when explanted in culture medium as compared to resting cells, whereas in vitro stimulation of resident MPM with IC resulted in enhanced lysosomal hydrolase release. IC-induced lysosomal secretion was time and dose dependent and varied with the nature of the complexes. Complement coated immune complexes (IC-CC) induced maximum enzyme secretion followed by IC-Eq and IC-Ag.
Insights
Mouse peritoneal macrophages (MPM) respond to immune complexes (IC) with altered morphology and protein content. Complement-coated ICs most effectively stimulated lysosomal enzyme release from these cells.
Area of Science:
- Immunology
- Cell Biology
Background:
- Mouse peritoneal macrophages (MPM) play a crucial role in immune responses.
- Immune complexes (IC) are formed by antigen-antibody interactions and can modulate macrophage function.
Purpose of the Study:
- To investigate the effects of preformed human serum albumin (HSA)-anti HSA immune complexes (IC) on MPM stimulation.
- To analyze the impact of different antigen-antibody ratios and complement coating on IC-induced macrophage responses.
Main Methods:
- MPM were stimulated in vivo and in vitro with various HSA-anti HSA ICs.
- Cellular morphology, protein content, 5' nucleotidase levels, and lysosomal enzyme activity were assessed.
- SDS-polyacrylamide gel electrophoresis was used to analyze cellular protein accumulation.
- Lysosomal hydrolase secretion was measured under different conditions.
Main Results:
- IC stimulation induced morphological changes, increased cellular protein, and decreased 5' nucleotidase in MPM.
- Specific protein bands (80, 47, 33, 28, 18, 14 kDa) accumulated in IC-elicited cells.
- Insoluble immune complexes at equivalence (IC-Eq) were more stimulatory than soluble antigen excess complexes (IC-Ag).
- In vitro IC stimulation enhanced lysosomal hydrolase release, while explanted IC-elicited cells showed reduced secretion.
- Complement-coated ICs (IC-CC) induced the highest enzyme secretion, followed by IC-Eq and IC-Ag.
Conclusions:
- MPM are sensitive to stimulation by HSA-anti HSA immune complexes.
- The nature and composition of ICs significantly influence the type and magnitude of macrophage response.
- Complement coating enhances the ability of ICs to induce lysosomal enzyme secretion from macrophages.