In this review, we summarize our investigations concerning the differential 
importance of CD14 and LBP in toll-like receptor 4 (TLR4)/myeloid 
differentiation protein-2 (MD-2)-mediated signaling by smooth and rough-form 
lipopolysaccharide (LPS) chemotypes and include the results obtained in studies 
with murine and human TLR4-transgenic mice. Furthermore, we present more recent 
data on the mechanisms involved in the induction of LPS hypersensitivity by 
bacterial and viral infections and on the reactivity of the hypersensitive host 
to non-LPS microbial ligands and endogenous mediators. Finally, the effects of 
pre-existing hypersensitivity on the course and outcome of a super-infection 
with Salmonella typhimurium or Listeria monocytogenes are summarized.