Distinctive effects of G-CSF, GM-CSF and TNFalpha on neutrophil apoptosis in systemic lupus erythematosus.
OBJECTIVE
To investigate the influence of culture with G-CSF GM-CSF and TNFalpha on neutrophil apoptosis, comparing neutrophils from SLE patients with rheumatoid arthritis (RA) patients and healthy control subjects.


METHODS
Neutrophils were isolated from SLE (n= 10), RA (n= 10) and healthy control subjects (n= 10), and cultured with two different concentrations of G-CSF, GM-CSF and TNFalpha. Proportion of apoptotic neutrophils at T=0, T=2hrs and T=24hrs was measured using FITC-labelled annexinV and flow cytometry.


RESULTS
Significantly more neutrophils were apoptotic at T=0 in the SLE subjects than in the other groups (median, range--Control 3.5% (0.3-7.9) SLE 9.5% (2.9-29.1) RA 3.0% (0.4-23.0) p<0.05). Following culture for 24 hours with 1ng/ml G-CSF the proportion of apoptotic neutrophils from SLE subjects was significantly increased (median, range = 51.6% (27.0-84.0) without G-CSF v 66.8% (31.8-89.2) with G-CSF p<0.05). This was not observed with RA or control subjects, in whom the trend was towards inhibition of apoptosis. Similar trends were seen with GM-CSF There was significant induction of apoptosis in SLE neutrophils after 2 hr culture with 1ng/ml TNFalpha (median, range = 2.3% (0.1-8.0) without TNFalpha v 5.2% (1.0-22.4) with TNFalpha). No significant change was seen in the other groups. There was an inverse correlation between total neutrophil count and the degree of induction of apoptosis by G-CSF and GM-CSF, determined at a range of time-points and cytokine concentrations


CONCLUSIONS
Neutrophils from SLE patients display resistance to the apoptosis-inhibiting effects of G-CSF and possibly GM-CSF, and appear more susceptible to the apoptosis-inducing action of TNFalpha, the greatest resistance being observed in the more neutropenic patients.
Armstrong
D J
DJ
United Hospitals Trust, Antrim, Co Antrim, UK. oswald17727@hotmail.com
Whitehead
E M
EM
Crockard
A D
AD
Bell
A L
AL
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis / Q000187:drug effects*; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000473:pathology / Q000503:physiopathology; D002452:Cell Count; D002478:Cells, Cultured; D005260:Female; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006304:Health Status; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000097:blood* / Q000473:pathology / Q000503:physiopathology; D008875:Middle Aged; D009504:Neutrophils / Q000187:drug effects* / Q000473:pathology; D012720:Severity of Illness Index; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D014409:Tumor Necrosis Factor-alpha; D016179:Granulocyte Colony-Stimulating Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor