Tuberculosis associated with infliximab, a tumor necrosis factor alpha-neutralizing agent.

BACKGROUND: Infliximab is a humanized antibody against tumor necrosis factor alpha (TNF-alpha) that is used in the treatment of Crohn's disease and rheumatoid arthritis. Approximately 147,000 patients throughout the world have received infliximab. Excess TNF-alpha in association with tuberculosis may cause weight loss and night sweats, yet in animal models it has a protective role in the host response to tuberculosis. There is no direct evidence of a protective role of TNF-alpha in patients with tuberculosis. METHODS: We analyzed all reports of tuberculosis after infliximab therapy that had been received as of May 29, 2001, through the MedWatch spontaneous reporting system of the Food and Drug Administration. RESULTS: There were 70 reported cases of tuberculosis after treatment with infliximab, for a median of 12 weeks. In 48 patients, tuberculosis developed after three or fewer infusions. Forty of the patients had extrapulmonary disease (17 had disseminated disease, 11 lymph node disease, 4 peritoneal disease, 2 pleural disease, and 1 each meningeal, enteric, paravertebral, bone, genital, and bladder disease). The diagnosis was confirmed by a biopsy in 33 patients. Of the 70 reports, 64 were from countries with a low incidence of tuberculosis. The reported frequency of tuberculosis in association with infliximab therapy was much higher than the reported frequency of other opportunistic infections associated with this drug. In addition, the rate of reported cases of tuberculosis among patients treated with infliximab was higher than the available background rates. CONCLUSIONS: Active tuberculosis may develop soon after the initiation of treatment with infliximab. Before prescribing the drug, physicians should screen patients for latent tuberculosis infection or disease.

Studies of marrow progenitor abnormalities in lupus-prone mice. II. Further studies of NZB Thy 1(neg)Lin(neg) bone marrow cells.

Bone marrow cells from NZB mice were fractionated and enriched in cells lacking surface markers characteristic of mature lineages, termed Thy 1neg Lineage(neg) cells. These cells represent approximately 1% of all marrow cells and constitute a much greater fraction of the bone marrow than do Thy 1lo Lineage(neg) cells. The NZB Thy 1neg Lineage(neg) cells were able to protect nonautoimmune, histocompatible DBA/2 recipients from lethal doses of irradiation, suggesting that this subpopulation contained progenitor cells. Consistent with this observation, fractioned Lip 6+ Thy 1neg Lineage(neg) cells, representing early B lineage cells, were less effective than Lip 6neg Thy 1neg Lineage(neg) cells in radioprotection. NZB marrow contains a great many more CFU-S than does marrow from nonautoimmune strains. DBA/2 mice transplanted with Thy 1neg Lineage(neg) cells from NZB marrow had substantial numbers of CFU-S, much greater than controls. This CFU-S potential was found primarily in the Lip 6neg Thy 1neg Lineage(neg) fractionated marrow, suggesting that that population contained early progenitor cells that had not yet differentiated into B lineage cells. Both radioprotection and increased CFU-S were transmitted serially by bone marrow from DBA/2 recipients of Thy 1neg Lineage(neg) NZB marrow to secondary and tertiary (irradiated) DBA/2 recipients. Also serially transplanted were precursors of antibody forming cells. These findings suggest that NZB Thy 1neg Lineage(neg) marrow cells play a critical role in the development of the abnormal phenotype of NZB mice. However, because this probably is not a homogeneous population, additional work will be necessary to define the surface and molecular properties of the cell or cells within the NZB Thy 1neg Lineage(neg) marrow population which serve as progenitors of the cells which mediate NZB disease.

Studies of bone marrow progenitor cells in lupus-prone mice. I. NZB marrow cells demonstrate increased growth in Whitlock-Witte culture and increased splenic colony-forming unit activity in the Thy-1-, lineage- population.

Previous studies have demonstrated that NZB marrow can transfer features of autoimmunity. Therefore, we undertook a study of NZB marrow to determine whether it demonstrated any phenotypic abnormalities. In Whitlock-Witte cultures, NZB marrow cells generated nonadherent cells at low seeding densities, densities at which marrow from other strains did not generate nonadherent cells. In contrast, NZB marrow grew less well than controls in Dexter cultures. Inasmuch as the latter favor growth of granulocyte-macrophage precursors and the former B cells, these results suggest a possible skewing of NZB marrow cells toward lymphocyte production. Unfractionated marrow cells from NZB mice were found to produce 10-fold more splenic colonies in lethally irradiated recipients than marrow cells from control mice. This result was independent of the genotype of the recipient. When the progenitor Thy-1lo, Lin- marrow subpopulation was studied, NZB mice did not differ substantially from controls regarding splenic CFU. Therefore, Thy-1-, Lin- marrow cells were studied as a possible source of the excess splenic CFU in NZB mice. Indeed, the NZB Thy-1-, Lin- population contained 30-fold more splenic CFU than did the Thy-1-, Lin- population from control mice. These results suggest that NZB mice have unusual marrow progenitor cells; such cells may play a role in their autoimmune disease.