ALBERT

Description: Dendritic cells (DC) are antigen-presenting cells involved in induction and regulation of immune responses. We investigated the impact of the number of infused and engrafted (day 28) dendritic cells, DC1 (lin−HLA-DR+CD11c+) and DC2 (lin−HLA-DR+CD123+) on the development of acute and chronic graft-versus-host disease (GVHD). Thirty three consecutive patients with hematological malignancies who underwent HLA-matched related G-CSF mobilized allogeneic PBSCT were included in the analysis. The mean follow up was 293 days (range: 36–417). There were 20 males and 13 females (median age: 29 years, range: 15–55). Conditioning regimen was myeloablative in 25 (Bu/Cy=13; Cy/TBI = 12) and non myeloablative in 8 patients (Flu/Mel = 7; Flu/Cy = 1). All patients received cyclosporine and short course methotrexate as GVHD prophylaxis. Three of them received steroids before day 28 for treatment of GVHD. Ten patients developed acute GVHD (grade II–IV) and 11 patients had chronic GVHD. The median DC2 count in the peripheral blood on day 28 was significantly lower among patients who developed acute GVHD as compared to those who did not and there was a trend to a lower count among patients with chronic GVHD [Table 1]. Based on the day 28 DC2 count patients were divided into a low DC2 quartile (2.3cell/ul, n=25). The two groups were comparable with regard to patient and graft characteristics (CD34, CD133, CD3, CD4, CD4CD45RO, CD4CD45RA, CD8, CD8CD45RO, CD8CD45RA, CD19, NK, DC1and DC2 cell dose). Patients in the low DC2 quartile group had higher probability of developing acute (P=0.000) and chronic GVHD (P= 0.022). Cox regression analysis revealed that low day 28 DC2 counts is associated with higher incidence of acute GVHD (HR=11.4; 95%CI=2.9–44.9; P=0.001) and chronic GVHD (HR=7.07; 95%CI=1.9–26.6; P=0.004). In a multivariate analysis which included other standard risk factors such as female to male transplants, conditioning regimen, CD34 and CD3 cell dose, low day 28 DC2 was found to be a risk factor for acute GVHD (HR=21.1; 95%CI=3–149.9; P=0.002) together with patient age (HR=1.1; 95%CI=1–1.3; P=0.039). DC1, DC2 counts in the graft and day 28 DC1 count did not correlate with the development of acute or chronic GVHD. Excluding patients who had developed acute GVHD before day 28 (n=3), a low day 28 DC2 count (