The role of macrophages in thymocyte mitogenesis

G. Mills, V. Monticone, V. Paetkau

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49 Scopus citations


The thymic lymphocytes of CBA/J mice respond to the mitogen Concanavalin A (Con A) only in the presence of adherent cells of the monocyte macrophage series. Depletion of adherent cells abrogates the response, and macrophage rich populations of cells restore it. The need for macrophages and mitogen is completely provided by irradiated splenic macrophages which have been exposed to Con A and washed free of the soluble mitogen. The mitogen macrophage effect in this case is apparently not due to soluble factors. Even more striking than the effect of macrophages on fresh cultures of thymic lymphocytes is their ability to restimulate quiescent cells 72 hr after their first stimulation with Con A. The quiescent cells respond immediately and quantitatively to Con A in the presence of fresh macrophages. This stimulation, like that of fresh thymocytes, is also controlled by a lymphokine (''costimulator'') produced by mixing macrophages, mitogen, and T lymphocytes. These data suggest a model in which two signals are required for mitogenesis. First, the interaction of macrophage, T cell, and mitogen elicits a soluble costimulator, which is itself not mitogenic. Secondly, in the presence of costimulator, the mitogen (either soluble, or, more efficiently, bound to macrophages) induces a proliferative response in the T cell.

Original languageEnglish (US)
Pages (from-to)1325-1330
Number of pages6
JournalJournal of Immunology
Issue number4
StatePublished - Dec 1 1976
Externally publishedYes

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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