Study of the protective effects of hyperimmune immunoglobulins G and M against endotoxin in mice and rats

Abstract

We prepared solutions of human IgM and IgG to various lipopolysaccharide (LPS) species. These were then tested, along with solutions of non-LPS specific human IgG or IgM, for their ability to confer passive immunity against experimental endotoxemia in two animal models. The immunoglobulins were first tested for an effect on the lethality induced by seven different LPSs in actinomycin-D sensitized mice, or by three different bacteria in normal mice. When the immunoglobulins were administered 1 h before challenge, a small protective effect was observed. This protection was dependent upon both the anti-LPS agent, the chemical composition of the LPS, or the strain of gram-negative bacteria used for injection. The anti-LPS IgM and IgG preparations reduced the mortality induced by Escherichia coli but not by Serratia marcescens or Klebsiella pneumoniae, indicating protection by strain-specific antibodies. When the antibodies were preincubated with LPS or bacteria for 30 min before administration, almost complete protection was seen. The influence of these immunoglobulin preparations or of human albumin (as a control) on the hypotensive and vascular-permeabilizing effects of LPS in rats was then studied. A dose-dependent inhibitory effect was observed with IgG preparations and albumin. At 200 mg/kg, anti-LPS IgG reduced the effects of LPS, while at 400 mg/kg, both anti-LPS and normal IgG preparations showed protection, as did human albumin used at the same dose. The IgM-enriched preparation worsened the initial hypotensive phase after LPS, whereas the anti-LPS IgM significantly reduced the second phase of the hypotension, but only at the largest dose of 400 mg/kg. In this second model using the rat, a clear difference between the activity of IgG and IgM was thus observed. We conclude that pretreatment with human immunoglobulins from large plasma pools modestly, but significantly, attenuated the effects of murine and rat Gram-negative sepsis, but that protection was incomplete. Our results suggest that single regimen intervention strategies may not be sufficient to influence the course of the disease.

Detection of anti‐TNFα activity in canine hyperimmune serum using a TNFα inhibition assay

“…Others have demonstrated that high‐dose intravenous IgG treatment down‐regulated plasma levels of proinflammatory IL6 and up‐regulated anti‐inflammatory IL4 in human trauma patients 30 . There are a number of studies demonstrating the beneficial therapeutic effect of hyperimmune immunoglobulins, anti‐LPS monoclonal antibodies, polyclonal immune globulin, and plasma exchange in cases of sepsis 31–35 . Similarly, it has been demonstrated that pretreatment with hyperimmune plasma before cardiac surgery improved outcomes 35,36 .…”

Influence of human anti-lipopolysaccharide immunoglobulins on tissue distribution and clearance of lipopolysaccharide in rats

“…A similar increase of the hematocrit was noted when a large dose of LPS was injected into immunized animals. This latter result con®rms that passive immunization does not protect rats against all pathophysiological eects of LPS [28], and suggests that the delayed increase in the uptake of LPS does not aord any signi®cant protection to the animals. It also demonstrates that the formation of LPS-IgG complexes in vivo may indeed be harmful to the animals.…”

“…Indeed, in our hands, we observed only a modest and incomplete protection of our anti-LPS IgG preparation against several dierent LPS and bacteria [28].…”

“…These preparations were used in an extensive screening of the eventual protective eect of passive immunization against LPS. The results of this latter study showed a very incomplete protection against some types of LPS and some bacteria [28].…”