Identification of non-HLA target antigens recognized after lung transplantation.

BACKGROUND: It has become evident that, besides cellular allogeneic immune responses against airway epithelial cells (AEC), humoral responses also contribute significantly to the pathogenesis of bronchiolitis obliterans syndrome (BOS) after lung transplantation (LTx). Antibody responses against transplanted lungs are directed against HLA and non-HLA antigens, but the identity of the latter antigens is presently unknown. METHODS: The main purpose of this study is to identify non-HLA target antigens on donor lungs recognized by patients' antibodies after LTx. Serum samples were taken before and 6 months after lung transplantation from 11 patients (4 men and 6 women, median age 44 years, range 18 to 63 years). Protein expression libraries were made from the luminal side containing AEC of discarded the donor bronchus, which was snap frozen in liquid N(2) during the organ harvesting procedure. Subsequently, all sera were analyzed for reactivity against library-encoded antigens by serologic analysis of recombinant cDNA expression libraries (SEREX). Recognized gene products were sequenced and analyzed by the NCBI/BLAST server. RESULTS: From a total of +/-3 x 10(4) gene products analyzed, six different non-HLA antigens were recognized by individual patient sera. Gene analysis indicated that they consisted of both polymorphic (PSMC4, F3, LOC284058, PLUNC, ZNF33A) and non-polymorphic (XP_931864) antigens. Cross-sectional analysis indicated that some antigens were recognized by 4 of 10 patient sera tested. CONCLUSIONS: Antibodies directed against non-HLA antigens are present after LTx, and can be identified using the SEREX technique. Identification of target antigens recognized after LTx will improve our understanding of the pathogenesis of BOS. Monitoring of the antibody response may be used to predict BOS.

Tumor necrosis factor alpha blockade reduces the synovial cell infiltrate early after initiation of treatment, but apparently not by induction of apoptosis in synovial tissue.

OBJECTIVE: To determine whether treatment with the chimeric anti-tumor necrosis factor alpha antibody infliximab could reduce cellularity by the induction of apoptosis in synovial tissue. METHODS: Twenty-four rheumatoid arthritis patients with active disease were randomized to receive either infliximab (3 mg/kg) (n = 12) or placebo (n = 12) intravenously. All patients were subjected to arthroscopic synovial biopsy directly before initiation of treatment. A second arthroscopic synovial biopsy of the same index joint was performed 48 hours after the first arthroscopy. After the second arthroscopy, the patients who had initially received placebo were also treated with infliximab in an extension study. A third arthroscopy was performed in all patients on day 28. Immunohistologic analysis was performed to characterize the cell infiltrate. In situ detection of apoptotic cells was performed by TUNEL assay and electron microscopy. RESULTS: At 48 hours after initiation of infliximab treatment, there was a significant reduction in the number of intimal macrophages; this was not observed in the placebo group. The number of sublining macrophages, T cells, and plasma cells also tended to be decreased in infliximab-treated patients, but not in the placebo group. Of interest, we did not detect any increase in the number of apoptotic cells after infliximab treatment. CONCLUSION: Infliximab therapy may reduce the number of inflammatory cells in rheumatoid synovial tissue as soon as 48 hours after initiation of treatment, but apparently not by induction of apoptosis. Conceivably, decreased cell infiltration primarily results from early inhibition of cell migration.