N. Ogawa et al., LYMPHOCYTE APOPTOSIS AND APOPTOSIS-ASSOCIATED GENE-EXPRESSION IN SJOGRENS-SYNDROME, Arthritis and rheumatism, 39(11), 1996, pp. 1875-1885
Objective. To study the mechanism and regulation of apoptosis in perip
heral blood T and B lymphocytes from patients with Sjogren's syndrome
(SS). Methods. The mode of in vitro lymphocyte death in the peripheral
blood of patients with SS was determined by fluorescence microscopic
analysis, terminal deoxynucleotidyl transferase assay, and DNA fragmen
tation analysis. Apoptotic cell death of T add B cells was determined
at 48 hours of culture by fluorescence-activated cell sorter analysis
of propidium iodide-stained cells, Messenger RNA (mRNA) expression of
bcl-2, bcl-x, bax, and c-myc in T and B cells was determined by enzyme
-linked immunosorbent assay-polymerase chain reaction (ELISA-PCR). Exp
ression of bcl-xL and bcl-xS was determined by Southern blot analysis
of PCR products. Gene expression was calculated as the ratio of each g
ene message to the message of the GAPDH gene. Bcl-2 protein levels in
SS T cells were determined by ELISA. Results. SS T cells showed increa
sed in vitro apoptosis compared with normal T cells (mean +/- SD 12.3
+/- 4.5% versus 7.3 +/- 2.0%; P < 0.01). Freshly isolated SS T cells s
howed increased expression of bcl-2 mRNA compared with normal controls
(mean +/- SD 1.50 +/- 0.65 versus 0.88 +/- 0.23; P < 0.05). There was
no significant difference in levels of bax or c-myc mRNA in T cells a
nd B cells between SS patients and normal controls, When SST lymphocyt
es were cultured in vitro for 72 hours, Bcl-2 protein levels decreased
with time. Conclusion. SS T cells showed accelerated apoptosis in vit
ro. Freshly isolated SS T cells had increased expression of bcl-2. An
increase in death-promoter signals and decrease in death suppressor si
gnals in vitro may have been responsible, in part, for the apoptosis i
n SS T lymphocytes.