Ceragenins are a group of cholic acid derivatives that have been chemically modified to make them cationic amphiphiles. Several of these derivatives exhibit antimicrobial activity against a broad range of bacteria. These compounds have advantages over cationic amphipathic peptides in that they are resistant to proteolysis and they incorporate stably into membranes. Although some forms of ceragenins are effective against both Gram-negative and Gram-positive bacteria, they are generally more potent against Gram-positive bacteria. Surprisingly, it is not the cell wall, but the high content of phosphatidylethanolamine in most Gram-negative bacteria that endow them with resistance. Ceragenins have the unusual property of forming complexes with phospholipids. Factors contributing to the mechanism of action of these agents are discussed. The ceragenins are a class of agents with many properties to make them favorable for application as antiinfective agents.
O’Leary et al. [ 75 ] and Paust et al. [ 76 ] showed that natural killer (NK) cells induced CHS reactions in RAG −/− mice (devoid of T- and B-cells). Further experimentation [ 77 ] showed that liver NK cells are able to transfer CHS to naive animals in 1 hour. Currently, there is no literature on how these NK cells become activated, although one can infer that NK cells are more likely to become activated due to a lack of engagement of inhibitory receptors. Ly49C, found on these hapten-specific NK cells, is specific for H-2 binding [ 78 ]. If the self-protein being presented is haptenated, it may no longer appropriately recognize or bind with the Ly49C, causing NK cells to recognize the cell as foreign. It is likely that DNP-bound MHC will affect Ly49C binding, but this requires experimental verification.