title: Expression of B7-1 costimulatory molecules in patients with multibacillary leprosy and reactional states.
abstract: BACKGROUND
  The expression of B7 as a costimulatory molecule on the surface of antigen-presenting cells such as macrophages and on dendritic cells characterizes the efficiency of the cell-mediated immune response.
  
  
  OBJECTIVE
  Our purpose was to evaluate B7-1 expression in peripheral blood mononuclear cells (PBMCs) immediately after cell isolation ('spontaneous' B7 expression), and in inflammatory cells from cutaneous lesions of patients with multibacillary leprosy (MB-L) without and during the reactional states of erythema nodosum leprosum (ENL) or reversal reaction (RR).
  
  
  METHODS
  Peripheral blood samples and skin biopsies of eight patients without (MB-L) and with reactional episodes (ENL and RR) were studied using antibodies against B7-1, CD1b, DR and CD14 in flow-cytometry and immunohistochemistry experiments.
  
  
  RESULTS
  The flow-cytometry studies (mean +/- SD% of fluorescent cells) revealed significant B7-1 expression on PBMCs isolated from patients with ENL (8.0 +/- 0.6%) and RR (15.0 +/- 1.4%) compared with that observed for patients with MB-L (0.4 +/- 0.2%). Similar results were observed for cutaneous lesions of these patients by immunohistochemical assays. One patient studied before and during ENL revealed weak B7 expression before the reactional episode (0.3% of cells) compared with the marked level of B7-expressing cells detected during ENL (8.5% fluorescent cells). Interestingly, an even higher B7 expression (15% of cells) was observed in patients with RR.
  
  
  CONCLUSIONS
  Our results strongly suggest that B7 expression precedes reactional episodes in MB-L, which could be related to the acquisition of effective immunity to Mycobacterium leprae during reactional episodes in leprosy. We propose B7 expression as a marker of CMI response in reactional episodes in leprosy.
authors.affiliation: Parasitology, Federal Fluminense University (UFF), Rio de Janeiro, Brazil. lacelauff@yahoo.com.br
authors.forename: D O
authors.initials: DO
authors.lastname: Santos
authors.forename: H C
authors.initials: HC
authors.lastname: Castro
authors.forename: S C
authors.initials: SC
authors.lastname: Bourguignon
authors.forename: O M
authors.initials: OM
authors.lastname: Bastos
authors.forename: C R
authors.initials: CR
authors.lastname: Rodrigues
authors.forename: H
authors.initials: H
authors.lastname: Van Heuverswyn
authors.forename: J A
authors.initials: JA
authors.lastname: Nery
authors.forename: A
authors.initials: A
authors.lastname: Miranda
mesh_terms: D018122:B7-1 Antigen / Q000276:immunology*; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D015440:Leprosy, Lepromatous / Q000276:immunology* / Q000473:pathology; D007963:Leukocytes, Mononuclear / Q000276:immunology*
chemical_list: D018122:B7-1 Antigen