FIBROSING ALVEOLITIS IN SYSTEMIC-SCLEROSIS - INCREASE IN MEMORY T-CELLS IN LUNG INTERSTITIUM

Despite the large numbers of T-cells present in the lungs in fibrosing alveolitis, their pathogenetic role is poorly understood. If these ce lls are involved in pathogenesis, they are more likely to express the CD45RO+ memory phenotype. To test this hypothesis, open lung biopsies from patients with fibrosing alveolitis associated with systemic scler osis (FASSc) were compared with grossly normal lung taken from the per iphery of lobes resected for lung cancer. Biopsies from eight patients with FASSc were compared with tissue from seven cancer controls. Para ffin sections were stained with a polyclonal anti-CD3 antibody For T-l ymphocytes, monoclonal anti-CD45 antibody for leucocyte common antigen , and monoclonal anti-CD45RO antibody for primed T-lymphocytes. Staini ng was assessed quantitatively by computerized image analysis: in each case, the number of inmunopositive cells was related to alveolar wall area and alveolar wall length. Mean alveolar wall thickness was incre ased in patients with FASSc (60.7+/-24.0 pm) compared with cancer cont rols (15.7+/-5.3 mu m). Patients with FASSc had greater numbers of CD4 5+, CD3+ and CD45RO+ cells . mm(-1) alveolar wall length compared with the controls. CD45RO+ cells made up 77%, (median) of the CD3+ cells i n FASSc, and their numbers per unit alveolar wall length were positive ly associated with alveolar wall thickness (r=0.61). In conclusion, in fibrosing alveolitis of systemic sclerosis, most interstitial T-lymph ocytes express the phenotype of memory cells; these cells are likely t o be involved in the persistent inflammatory process.