NEW EVIDENCE FOR EXISTENCE OF LONG LIVED MACROPHAGES

PROLONGED observation of labelled macrophages within inflammatory reactions in the ear chambers of rabbits has led to the suggestion that some of these cells may be very long lived1,2. Objective evidence in favour of the existence of long lived macrophages has, however, been lacking. In addition, study of granulomata induced by complete Freund adjuvant indicates a high rate of turnover of participating macrophages, with no evidence of persistence beyond 1-2 weeks of the mononuclear cells that originally emigrated into the lesion from the circulation3. We have found a similar high rate of turnover among the macrophages in chronic inflammatory reactions provoked by B. pertussis vaccine or paraffin oil. © 1969 Nature Publishing Group.