Five reciprocal cycles of subtractive hybridization using cDNA generated from fibroblasts with normal lipopolysaccharide (LPS) responsiveness (lps(n)) and from hyporesponsive (lps(d)) fibroblasts have led to the finding that caveolin-1 is expressed at markedly higher levels of mRNA in lps(d) than in lps(n) fibroblasts. Caveolin-1 message can also be readily detected via reverse transcription-PCR in the RAW264.7 and J774.1 macrophage-like cell lines as well as in primary thioglycolate (TG)-elicited mouse peritoneal macrophages. In RAW264.7 cells, both caveolin-1 mRNA and protein levels are down-regulated by LPS. In TG-elicited C3HeB/FeJ peritoneal macrophages, in contrast, expression of both caveolin-1 protein and mRNA is up-regulated in vitro in response to LPS stimulation. The up-regulation of caveolin-1 protein expression in C3HeB/FeJ peritoneal macrophages can be demonstrated at concentrations as low as 1.0 pg of LPS/ml. However, LPS concentrations approximately 4 orders of magnitude higher (10(4) pg/ml) were required to stimulate the LPS-hyporesponsive C3H/HeJ mice peritoneal macrophages such that significant caveolin-1 protein up-regulation was detected. Caveolin-1, a principal component of plasmalemmal caveolae, has been reported as a potentially important regulator for signal transduction during cellular stimulation. The results described in this report suggest that caveolin-1 expression may be associated with LPS signaling/internalization.