ALVEOLAR MACROPHAGES IN SARCOIDOSIS COEXPRESS HIGH-LEVELS OF CD86 (B7.2), CD40, AND CD30L

Alveolar macrophages (AM) from sarcoid patients have been shown to be good antigen presenting cells (APC) unlike normal AM which are usually ineffective. We demonstrate in ten consecutive sarcoid patients that most of their AM, unlike normal AM, do coexpress high levels of CD86, CD40, and CD30L, all known to be important for T-cell activation. CD80 is also slightly more expressed on sarcoid AM than on normal AM, but is detected on only 26 +/- 6% (mean +/- SEM) of sarcoid AM. A good cor relation is present between the percentage of sarcoid AM expressing CD 86 and CD40 or CD86 and CD30L. However, no correlation is found betwee n the percentage of CD80 and CD86 positive AM in these same patients. Blocking antibodies against CD86 were able to reduce by more than 80% allogeneic T-cell proliferation induced by the AM of sarcoid patients. This study provides evidence that AM can, in pathologic states such a s sarcoidosis, express functional costimulatory molecules for T-cell a ctivation such as CD86, thought to be rather specific for more profess ional APC such as dendritic cells.