1471-2172-2-2.fm BMC Immunology (2001) 2:2 http://www.biomedcentral.com/1471-2172/2/2 BMC Immunology (2001) 2:2Research article Changes in human lymphocyte subpopulations in tonsils and regional lymph nodes of human head and neck squamous carcinoma compared to control lymph nodes Berta Vidal-Rubio1, Marta Sanchez-Carril2, Josefina Oliver-Morales3, África González-Femandez2 and Francisco Gambón-Deza*1 Address: 1Unit of Immunology, Meixoeiro Hospital, Vigo, Spain, 2Department of Immunology, Faculty of Sciences, Vigo University, Vigo, Spain and 3Department of Pathology, Meixoeiro Hospital, Vigo, Spain E-mail: Berta Vidal-Rubio - [email protected]; Marta Sanchez-Carril - [email protected]; Josefina Oliver- Morales - [email protected]; África González-Femandez - [email protected]; Francisco Gambón-Deza* - [email protected] *Corresponding author Abstract Background: Lymphoid tissues constitute basic structures where specific immune responses take place. This leads to the development of germinal centres (GCs), migration of cells and the generation of memory cells. Here, we have compared human tumour reactive lymph nodes and tonsils with control lymph nodes. Results: The study by flow cytometry shows that in control lymph nodes the majority of cells were naive T-lymphocytes (CD45RA+/CD7+). In reactive nodes, although the percentage of CD45RO+ T cells remains constant, there is an increase in the number of B-lymphocytes, and a reduction in naive T cells. The percentage of cells expressing CD69 was similar in reactive nodes and in controls. In both cases, we have found two populations of B cells of either CD69- or CD69dull. Two populations of T cells, which are either negative for CD69 or express it in bright levels (CD69bright), were also found. The analysis of tissue sections by confocal microscopy revealed differences between control, tonsils and tumor reactive lymph nodes. In control lymph nodes, CD19 B cells are surrounded by a unique layer of CD69bright/CD45RO+ T cells.