Postoperative prognosis of pulmonary adenocarcinoma subtypes correlates with HLA-DR expression and the number of tumor-infiltrating cells

Human pulmonary adenocarcinomas (AC) can be divided into two types with special morphologic and immunohistologic properties and a different number of tumor-infiltrating cells as shown by previous investigations. In the present study the relevance of this subdivision for patients' survival was investigated. 42 surgically resected pulmonary AC of stage I and II were subclassified using light and electron microscope. For immunohistologic phenotypization, reactions with monoclonal antibodies against HLA-DR, CD1 and CD3 were studied on fresh tumor specimens. Postoperative survival was evaluated after at least 24 months. AC of type I (N=23) with mucin production and ultrastructural properties of goblet cells showed almost no HLA-DR expression. Infiltration by CD1-positive dendritic cells Langerhans cells and CD3-positive T lymphocytes was significantly lower than in AC of type II (N=19), which expressed HLA-DR homogeneously and showed, ultrastructurally, Clara cell and/or type II pneumocyte properties. Patients' outcome was similar in stage I AC of both types: about 70% of patients were still alive after 24 months. However, significant differences were found between the two types in stage II AC with regional lymph node metastases: survival of patients with AC of type II corresponded roughly with stage I tumors (67%) but only 20% of patients with type I AC were still alive after 24 months. These results indicate that postoperative prognosis for patients with pulmonary AC of type II is more favourable than for mucinous AC of type I. This may be due to the homogeneous HLA-DR expression and higher number of immunologically competent tumor-infiltrating cells which possibly results in better tumor surveillance.