Am. J. Respir. Cell Mol. Biol., Vol 17, No. 4, Oct 1997, 414-421.
The lung as a source and a target organ for T- and B-lymphocytes
T Tschernig, K Boeke, G Steinhoff, K Wonigeit, R Pabst and J Westermann
Department of Functional and Applied Anatomy, Medical School of Hannover, Germany. Tschernig.Thomas@MH-Hannover.DE
In lung transplantation, a substantial number of donor leukocytes are
transferred from the donor to the recipient by the graft. Using a rat
model, it was analyzed in this study to what extent leukocytes leave the
lung, to which phenotype they belong, and to which organs they migrate. The
model used was the orthotopic transplantation of the left lung of
LEW.7B(RT7b) rats into LEW(RT7a) recipients. Lung allografts are not
rejected in this strain combination, which differs only in the RT7 system,
a genetic polymorphism of CD45. Using the RT7b marker (monoclonal antibody
His41), the distribution of donor leukocytes passively transferred with the
graft was studied by immunohistology 2 wk after transplantation. At this
time, 2.9 +/- 0.1% (n = 6) of the peripheral blood leukocytes in the
recipients were derived from the donor lung. The donor cell population
detected in the blood consisted of T cells (59 +/- 4%), B cells (5.1 +/-
0.2%) and a surprisingly high fraction of natural killer (NK) cells (36 +/-
3%). No monocytes or granulocytes were found. In lymph nodes, spleen and
thymus donor- derived T- and B-cells could be shown in typical T- and
B-areas, respectively. Donor-derived leukocytes were found in the liver and
the skin. In the tissue and the bronchoalveolar lavage (BAL) of the host
lung, predominantly T cells were found. Furthermore, in the donor tissue
and BAL more than 70% of T- and B-cells were host type, demonstrating that
the donor lung had been repopulated to a great extent by host lymphocytes.
This supports the relevance of BAL as a diagnostic tool in lung diseases.
Thus, the lung is an immunologically important site, releasing lymphocytes
which migrate to other organs and also attracting many lymphocytes from the
circulation.