T Cell Activation by Antigen-Presenting Cells From Lung Tissue Digests: Suppression by Endogenous Macrophages

Clin Exp Immunol. 1985 Dec;62(3):586-93.


Parechymal cells (PC) were prepared by digestion of perfused, lavaged rat lung in a mixture of collagenase and DNase, and harvested on a discontinuous percoll gradient. The process yielded on average 1.0 X 10(8) viable cells/gram tissue. PC were pulsed with soluble antigen, and tested for their capacity to trigger antigen-specific activation of immune T-cells in vitro, or to replace adherent accessory cells necessary for Concanavalin A (Con A)-induced T-cell proliferation. Unfractionated PC exhibited only minor antigen-presenting cell (APC) activity. However, removal of adherent or FcR-positive cells unmasked substantial APC activity. Subsequent experiments indicated that the majority of the APC banded at the top of the percoll gradient (density less than 1.048 g/ml). The same cell preparations substituted for adherent accessory cells in Con A- activation of T cells, suggesting capacity to secrete soluble factors such as interleukin-1 (IL-1) as well to present antigen. The PC preparation also contained T-cells, which were refractory to Con A stimulation unless endogenous adherent cells were first removed. Collectively, these data suggest the presence of non-adherent, FcR-negative, low density accessory cells in the lung parenchyma, capable of both APC activity and soluble factor production. Their T-cell-activation functions appear to be down regulated by endogenous adherent, FcR-positive cells. It is speculated that the accessory cells in these lung preparations may be dendritic cells, the activity of which is subject to inhibition by macrophages.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigen-Presenting Cells / immunology*
  • Cell Separation
  • Centrifugation, Density Gradient
  • Concanavalin A / pharmacology
  • Female
  • Immune Tolerance
  • Lung / cytology*
  • Lymphocyte Activation*
  • Macrophages / immunology*
  • Rats
  • Rats, Inbred Strains
  • T-Lymphocytes / immunology*


  • Concanavalin A