Expression of B7-1 costimulatory molecules in patients with multibacillary leprosy and reactional states.
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.
Santos
D O
DO
Parasitology, Federal Fluminense University (UFF), Rio de Janeiro, Brazil. lacelauff@yahoo.com.br
Castro
H C
HC
Bourguignon
S C
SC
Bastos
O M
OM
Rodrigues
C R
CR
Van Heuverswyn
H
H
Nery
J A
JA
Miranda
A
A
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*
D018122:B7-1 Antigen