Determinants of soluble CD23 antigen levels in hemodialysis patients: effect of 1.25 dihydroxyvitamin D3 and recombinant human erythropoietin treatment.
BACKGROUND
The immunodeficiency of end-stage renal disease (ESRD) paradoxically coexists with T cell and monocyte activation. In spite of well known defective antibody responses in ESRD, the functional status of B cells in the immune system dysregulation of uremia is still controversial. Soluble CD23 (sCD23) antigen is a recently identified B cell activation marker and is also involved in T cell activation process. Effects of parathyroid hormone (PTH), red blood cells and ferritin on T and B cell functions have been shown both in vivo and in vitro.


METHODS
In this study, serum levels of sCD23 in hemodialysis patients were determined to evaluate the functional status of B cells and possible linkages between this cytokine and PTH levels, ferritin levels, red blood cell counts were investigated.


RESULTS
Serum sCD23 levels were significantly elevated in hemodialysis patients relative to healthy controls (12.5+/-8.4 micro/l vs. 2.4+/-1.1 micro/l, p<0.001). Serum sCD23 levels were negatively correlated with red blood cell count (r = -0.61, p = 0.009) and serum PTH levels (r = -0.62, p = 0.008), while positively correlated with serum ferritin levels (r = 0.63, p = 0.007) in hemodialysis patients. We also investigated the immunumodulator effects of 1.25 dihydroxyvitamin D3 (1.25OHD3) and recombinant human erythropoietin (rHu-Epo) treatment in hemodialysis patients. 1.25OHD3 treatment for eight weeks did not change serum sCD23 levels in hemodialysis patients (n = 8). On the other side, rHu-Epo administration for 16 weeks led to a decrease in serum sCD23 levels (17.7+/-8.6 microg/l vs. 9.8+/-3.5 microg/l, p = 0.007) in these patients (n = 9).


CONCLUSIONS
These results suggests that similar to T cells, B cells are activated in uremia and the degree of this activation is correlated with red blood cell count, serum parathyroid hormone levels and iron status of the hemodialysis patients. Moreover, B cell activation could be altered by recombinant human erythropoietin therapy in hemodialysis patients.
Altun
B
B
Department of Internal Medicine, Hacettepe University Faculty of Medicine, Ankara, Turkey.
Erdem
Y
Y
Usalan
C
C
Arici
M
M
Haznedaroglu
I C
IC
Yasavul
U
U
Turgan
C
C
Caglar
S
S
Kirazli
S
S
D000328:Adult; D001402:B-Lymphocytes / Q000276:immunology*; D002117:Calcitriol / Q000627:therapeutic use*; D016022:Case-Control Studies; D004921:Erythropoietin / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000276:immunology* / Q000628:therapy; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology; D008297:Male; D017455:Receptors, IgE / Q000097:blood*; D011994:Recombinant Proteins; D006435:Renal Dialysis
D017455:Receptors, IgE; D011994:Recombinant Proteins; D004921:Erythropoietin; D002117:Calcitriol