Bacterial lipopolysaccharides in sterile corneal organ-culture media

Purpose. Lipopolysaccharides (LPS) are known to stimulate various inflammat ory reactions by interaction with cytokines and macrophages. As contaminati on of sterile organ culture media with nonviable bacterial substances may i nfluence donor tissue prognosis, we investigated a series of culture media drawn from organ culture for the presence of LPS. Methods. One hundred eigh ty-two samples of sterile organ-culture media were tested for LPS using the Limulus-amoebocyte-lysate assay (LALA). We then investigated the time cour se of LPS levels during organ culture, the influence of medium changes, the graft deswelling procedure and transportation as well as repeated freezing on the detection of lipopolysaccharides with the LALA. Results. LPS above background threshold was found in 21.4% of the organ-culture media. The tim e course of LPS during organ culture and through the deswelling procedure w as quite stable. Medium changes may wash out LPS, thus the highest LPS valu es were normally seen in the examination medium, which has the first contac t with the corneal tissue. Repeated freezing did not influence the detectab ility of LPS with the LALA. Conclusion. LPS detected in sterile corneal org an cultures is probably derived From nonreplicating bacterial postmortem do nor tissue contamination. It is a rather heat and cold stable product that may be washed out from the donor tissue by medium changes. As LPS may direc tly influence graft viability or trigger inflammatory host responses, furth er investigations of the clinical course of these grafts are required.