[1243] Paracortical Population of CD11c+CD8-DC Dendritic Cells in Angioimmunoblastic T-Cell Lymphoma.

Sugganth Daniel, Violette Ghali. St. Lukes Roosevelt Hospital, New York, NY; Beth Israel Medical Center, New York, NY

Background: CD11c+dendritic cells (DC) are highly potent antigen presenting cells critical to T-cell stimulation, endothelial proliferation and antigenic response in the lymph node. CD11c+CD8-DC have upto ten times the potency of CD11c+CD8+DC in producing a CD4 T-cell proliferative response. The latter can induce apoptosis of CD4 T-cells thereby regulating the response. CD11c+DC have also been clearly established to drive lymph node vascular proliferation and have also been shown to have capability to differentiate into endothelial cells. Angioimmunoblastic T-Cell lymphoma (AITL) is characterized by neoplastic T-cells in the paracortex, prominent vascular proliferation and expanded dendritic meshworks.
Design: Paraffin embedded lymph nodes from 9 cases of AITL including one with features suggestive of HIV lymphadenopathy and one with hyperplastic features were stained for CD11c a mature dendritic cell marker, CD21 for follicular dendritic cells, CD1a for immature dendritic cells and CD8 for expression on dendritic cells.
Results: CD11c membrane positivity was observed for a population of DC located primarily in the paracortex and largely perivascular in arrangement and this population was uniformly negative for CD8. CD11c positivity was in focal clusters in the case with features of HIV lymphadenopathy and occassional in the case with hyperplastic features.CD21 stained DC overlapping most CD11c positive areas however was more predominant within residual and expanded follicles. CD1a was positive in rare cells in two cases.


Conclusions: A distinct predominantly paracortical population of CD11c+CD8-DC largely arranged in a perivascular pattern is identified in this study. These cells have been shown to have potent CD4 T-cell proliferative capabilities and accelerate vascular proliferation. The presence of these histopathologic features in AITL requires further work to elucidate the functional implications of these CD11c+ dendritic cells. References: 1. A Subclass of Dendritic Cells Kills CD4 T cells Via Fas/Fas-Ligand-induced Apoptosis. JEM Vol.183 1996. 2. Regulation of lymph node vascular growth by dendritic cells. JEM Vol. 203 2006. 3. The role of dendritic cell precursors in tumour vasculogenesis. Br J Can 2005 92.
Category: Hematopathology

Monday, February 28, 2011 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 170, Monday Morning

 

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