The mechanism of bone marrow‐derived (B) lymphocyte activation. II. A “second signal” for antigen‐specific activation provided by flagellin and lipopolysaccharide

摘要

AbstractEvidence is presented that the activity of polymerized flagellin (POL) in allowing spleen cells from congenitally athymic (nu/nu) mice to respondin vitroto the thymus‐dependent antigen fowl IgG (FGG), is due to an intrinsic property of the POL molecule, rather than to some minor contamination of the preparation by lipopolysaccharide (LPS). While LPS prepared from the sameSalmonellastrain as was the POL was shown to be active in the present system, the potency of the LPS was not sufficient to account simply for the activity of the POL preparation in the light of its possible endotoxin content. Additionally, the activity of the POL was shown to be susceptible to treatment by the proteolytic enzymes, trypsin and pepsin. Thus, it is shown that two substances, one a protein, the other a LPS, share the property of allowing bone marrow‐derived (B) cells to be triggered by antigen in the absence of thymus‐derived (T) cells. A basis for the common action of LPS and the protein POL was sought in their shared polymeric nature. However, the monomeric form of flagellin, even when oxidized so that it did not repolymerize under stringent conditions, was still active, suggesting that the situation is more co