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Marked reduction of mouse peritoneal CD5+ B cells by intraperitoneal administration of lipopolysaccharide
1Department of Microbiology and Immunology, Aichi Medical University, Nagakute, Japan.
Abstract:
Intraperitoneal administration of lipopolysaccharide to mice induced a marked reduction of CD5+ B cells in the peritoneal cavity. The reduction was not induced by intravenous, subcutaneous, or oral administration of lipopolysaccharide. The reduction continued for about 10 days after the injection, and the CD5+ B-cell count recovered to the normal state about 14 days after the injection. The reduction of peritoneal CD5+ B cells might be caused by apoptotic cell death. Injection of lipopolysaccharide did not result in production of antibody to lipopolysaccharide. On the other hand, intraperitoneal injection of heat-killed bacteria did not induce a reduction of peritoneal CD5+ B cells and elicited the definite production of antibody to lipopolysaccharide.
Insights
Intraperitoneal lipopolysaccharide administration significantly reduced peritoneal CD5+ B cells in mice, likely via apoptosis. This reduction recovered within 14 days, unlike antibody production, highlighting route-specific immune responses.
Area of Science:
- Immunology
- Cell Biology
- Microbiology
Background:
- Lipopolysaccharide (LPS) is a key component of Gram-negative bacterial outer membranes.
- B cells play a crucial role in adaptive immunity, with distinct subsets like CD5+ B cells.
- The route of antigen administration can significantly influence immune responses.
Purpose of the Study:
- To investigate the effect of lipopolysaccharide administration route on peritoneal CD5+ B cells.
- To determine the kinetics of CD5+ B cell reduction and recovery.
- To explore the potential mechanism of CD5+ B cell reduction and its relation to antibody production.
Main Methods:
- Mice were administered lipopolysaccharide via intraperitoneal, intravenous, subcutaneous, or oral routes.
- Peritoneal lavage was performed to quantify CD5+ B cell populations.
- Antibody production to lipopolysaccharide and heat-killed bacteria was assessed.
Main Results:
- Intraperitoneal lipopolysaccharide administration markedly reduced peritoneal CD5+ B cells.
- This reduction persisted for approximately 10 days, with recovery by 14 days post-injection.
- Intraperitoneal lipopolysaccharide did not induce anti-LPS antibody production, whereas heat-killed bacteria did.
Conclusions:
- Intraperitoneal administration of lipopolysaccharide specifically targets and reduces peritoneal CD5+ B cells, potentially through apoptosis.
- The observed reduction is transient, with immune cell populations returning to baseline levels.
- Route-dependent immune responses are critical; intraperitoneal LPS induces cell depletion without antibody production, unlike whole bacterial challenge.