Lymphocyte collaboration is not required for the induction of murine macrophage procoagulant by endotoxin.

The putative requirement for lymphocytes as instructor cells in the induction of macrophage procoagulant (PCA) by endotoxin (LPS) was tested on elicited mouse peritoneal macrophages and on bone marrow-derived macrophages. Percoll purification of thioglycollate macrophages to at least 99.8 percent failed to diminish PCA induction by LPS. Bone marrow macrophages synthesized most PCA in response to LPS when they constituted more than 95 percent of the cells. In addition, PCA synthesis by these cells was not enhanced by the addition of splenic lymphocytes in a ratio of four to one. Exudate macrophages from endotoxin unresponsive C3H/HeJ mice failed to increase PCA synthesis in the presence of LPS. The addition of responsive C3H/HeN splenic lymphocytes to non-responsive HeJ macrophages did not permit LPS to induce the synthesis of PCA, suggesting the absence of unidirectional lymphocyte-instructed pathway. These data provide no evidence for lymphocyte collaboration in the LPS induction of murine macrophage PCA. LPS appears to induce PCA by acting directly on the macrophage.