Distribution of p24 HTLV3 major core protein in lymph nodes of LAS patients.

: Lymph nodes of patients with lymphadenopathy syndrome (LAS) are characterized by two main histological patterns: hyperplastic reactive (H) and regressive (R). In both conditions, the paracortex (PC) is markedly activated with presence of selectively Ia-1+ high endothelial venules. Using a monoclonal antibody for p24, the major core protein of HTLV3, we have immunohistochemically determined the distribution of p24+ cells in lymph nodes from 23 LAS patients' HTLV3-ab serologically positive. p24+ cells were demonstrated in 11 cases. Control nodes were negative. p24+ cells included high endothelial cells of PC postcapillary venules, large perivenular cells, large mono- or binucleated cells in PC and in GC, and few lymphocytelike cells. Our preliminary observations indicate that the majority of p24+ cells are high endothelial and accessory cells that may act either as virus reservoir or as antigen-presenting cells to T4 lymphocytes and to GC B cells. In addition, the positivity of high endothelial cells for p24 might help to explain their selective Ia-1+.