To determine the effect of burn injury on humoral immunity, we followed the murine primary and secondary antibody responses to sheep erythrocytes (SRBC), a T-cell dependent antigen, and lipopolysaccharide (LPS), a T-cell-independent antigen, after 25% TBSA burn. Splenic B-cell-specific antibody synthesis was measured by a hemolytic plaque assay. Simultaneous measurements of specific and nonspecific immunoglobulins were performed by a hemagglutination assay and radial immunodiffusion, respectively. Numbers of splenic primary anti-SRBC-plaque forming cells (PFC) were generally equal in burn and control groups. Numbers of splenic secondary IgG anti-SRBC and anti-LPS PFCs were significantly increased in the burn group with a peak at 5 and 16 days after secondary immunization. There were no differences in serum anti-SRBC or anti-LPS antibody titers between burn-injured and control mice. Nonspecific serum IgG levels were depressed on Days 5 and 10 following injury but had returned to normal by Day 10. Due to the discrepancy between increased secondary PFCs and normal or decreased serum immunoglobulin levels, we measured clearance of exogenously administered IgG. The half-life of IgG in burn mice was 2.5 days compared to 7.1 days in control (P less than 0.05). In conclusion, the antibody response is enhanced after burn injury in the mouse, but this is not reflected in serum levels of specific antibody or immunoglobulins probably due to increased clearance from the circulation.
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