THE IMMUNOLOGICAL ARCHITECTURE OF B-LYMPHOCYTE AGGREGATES IN CRYPTOGENIC FIBROSING ALVEOLITIS

Cryptogenic fibrosing alveolitis (CFA) is believed to have a pathogene sis mediated by the cellular arm of the immune system, Previous studie s have, however, indicated the presence of B-lymphocyte aggregates, as well as evidence of local immunoglobulin production and increased lev els of B-cell growth factors, It has recently been shown that CFA is a ssociated with the production of circulating IgG autoantibodies to ant igen(s) associated,vith alveolar lining cells, This prompted an examin ation of the immunological architecture of the B-lymphocyte aggregates , in order to assess whether they might provide histological confirmat ion of a local humoral immune response in these patients. Thirty-eight consecutive open lung biopsy specimens mere examined from patients wi th CFA and aggregates of B lymphocytes were identified in 37/38. In on ly five cases mere germinal centres seen. The morphological appearance s of the aggregates were reminiscent of those observed in mucosal asso ciated lymphoid tissue (MALT). Using immunohistochemistry, despite the low frequency of true germinal centre formation, the B-lymphocyte agg regates were shown to contain the cellular micro-environment necessary for a humoral immune response, In addition, there was evidence of lym phocyte proliferation and activation within these aggregates, These re sults provide evidence of a local humoral immune response associated w ith B-lymphocyte aggregates in the lungs of patients with CFA.