A W Thomson

Publications (2)7.11 Total impact

• Article: Circulating dendritic cell subset levels after allogeneic stem cell transplantation in children correlate with time post transplant and severity of acute graft-versus-host disease.

  J Vakkila, A W Thomson, L Hovi, K Vettenranta, U M Saarinen-Pihkala
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  ABSTRACT: We examined the recovery of circulating monocytoid (Lin- CD11+ HLA-DR+) and plasmacytoid (Lin- CD123+ HLA-DR+) precursor (pre) dendritic cell (DC) subsets after allogeneic stem cell transplantation (SCT) in 39 children, using age-matched healthy children as controls. The frequencies of DCs in peripheral blood samples were determined by flow cytometry. The initial recovery of DC occurred simultaneously with myeloid engraftment. However, with time, DC subset values declined, being very low 40-50 days after SCT. Low monocytoid and plasmacytoid DC values were associated significantly with the development of severe acute graft-versus-host disease (aGVHD) (P=0.042 and 0.017, respectively). Plasmacytoid DC values were lower than in the age-matched controls for the entire follow-up period (range 102-2569 days), although, with time, values approached normal levels. Normal monocytoid DC numbers were observed within 300-400 days post SCT. The severity of chronic GVHD did not correlate with quantitative recovery of DC. We conclude that in pediatric SCT, initial recovery of DC production is concurrent with that of myelopoiesis, yet with time, DC subset values decline and low counts are associated with severe aGVHD. Monocytoid DC numbers approach normal levels within a year of SCT, but plasmacytoid DC counts recover very slowly.
  Bone Marrow Transplantation 04/2005; 35(5):501-7. · 3.75 Impact Factor
• Article: Dendritic cell subsets in childhood and in children with cancer: relation to age and disease prognosis.

  J Vakkila, A W Thomson, K Vettenranta, H Sariola, U M Saarinen-Pihkala
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  ABSTRACT: Dendritic cells (DC) are a heterogeneous group of uniquely well-equipped bone marrow-derived antigen-presenting cells. They circulate in blood as precursor cells (preDC). In humans, two blood-borne subtypes of preDC can be distinguished by their differential expression of CD11c (CD11c+ preDC; monocytoid DC) and CD123 (CD123+ preDC; plasmacytoid DC). We studied the incidence of monocytoid and plasmacytoid DC in peripheral blood samples from 39 children of various ages (0.4-16.8 years) by flow cytometry, and found a significant negative correlation between the number of plasmacytoid DC and age (r = 0.421, P = 0.012). Monocytoid DC counts did not change significantly with age. Similarly, we analysed DC subsets in 19 children with cancer at the time of diagnosis prior to initiation of any myelosuppressive or antiproliferative treatment and compared the results with those obtained from gender- and age-matched control children. Patients with cancer had significantly less circulating monocytoid DC than controls (medians 13.2 versus 21.4 cells/ micro l, respectively, P = 0.042) at diagnosis, whereas absolute plasmacytoid DC counts did not differ significantly between the study groups. However, clinical outcome of the children with cancer (2.9-5 years follow-up after diagnosis) correlated with plasmacytoid DC count. Children with high plasmacytoid DC counts at diagnosis (above median) survived significantly worse (6/10 deceased) than those with low counts (1/9 deceased) (P = 0.034). Thus, circulating plasmacytoid DC counts are related to age during childhood, and development of cancer is associated with low number of monocytoid DC. A low circulating plasmacytoid DC count at diagnosis was a good prognostic sign.
  Clinical & Experimental Immunology 04/2004; 135(3):455-61. · 3.36 Impact Factor