[Expression of adhesion molecules in transplanted lung allografts--immunohistochemical study using the rat lung...

I have carried out orthotopic left lung transplantation in rats in order to investigate role of adhesion molecules and the time course of lung allograft rejection. I used an RT-1-incompatible rat lung allograft model and examined the time course of organ rejection and the expression of ICAM-1 and LFA-1 molecules in two combinations of inbred rat strains, WKAH/Hkm and F344/NS1c. Four rejection phases of rejection appeared sequentially in grafts of both combinations, resulting in complete rejection within seven days after transplantation. Immunohistochemical study analysis using R1-3B3 antibody showed that the mononuclear cells infiltrating into the rejected grafts proved to be T lymphocytes and their number increased according to the stage of rejection. ICAM-1 detectable in the normal lung, was also detected on the pneumocyte cell surface at all stages of acute rejection, suggesting that pneumocytes were target cells for LFA-1 positive cells. On the other hand, LFA-1 was expressed by mononuclear cells located around the venules at stages of mild-moderate rejection. This finding suggested that LFA-1 positive cells play important roles in the early stages of acute rejection especially in areas surrounding the venules. These data suggested that ICAM-1 and LFA-1 participate in the course of acute lung allograft rejection.