Premium
IRTA1 + monocytoid B cells in reactive lymphadenitis show a unique topographic distribution and immunophenotype and a peculiar usage and mutational pattern of IgV H genes
Author(s) -
Lazzi S,
Bellan C,
Tiacci E,
Palummo N,
Vatti R,
Oggioni M,
Amato T,
Schuerfeld K,
Tonini T,
Tosi P,
Falini B,
Leoncini L
Publication year - 2006
Publication title -
the journal of pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.964
H-Index - 184
eISSN - 1096-9896
pISSN - 0022-3417
DOI - 10.1002/path.1944
Subject(s) - biology , immunophenotyping , germinal center , marginal zone , population , lymph node , gene , b cell , pathology , antigen , genetics , immunology , antibody , medicine , environmental health
The origin and function of monocytoid B cells (MBCs) are poorly understood. Taking advantage of their strong expression of IRTA1 (a receptor that is also associated with MALT marginal zone B cells), we have comprehensively analysed MBCs in 25 cases of lymphadenitis of different aetiologies, shedding new light on the topographical distribution, immunophenotype and IgV H gene usage and mutational profile of this B cell subset. IRTA1 + MBCs, although predominantly located in the subcapsular and intermediary sinuses, were also observed scattered within germinal centres (GCs) in all lymphadenitis cases examined. The molecular characterization of IgV H genes revealed that IRTA1 + MBCs residing in different areas of the lymph node (subcapsular sinus, intermediary sinuses and GCs) can be clonally related (with intraclonal variation), and that those located in GCs are consistently more mutated and selected for expression of a functional antigen receptor than those located in the sinuses. Moreover, by contrast, IRTA1 + MBCs in GCs express the memory B cell marker CD27. Finally, in toxoplasmic lymphadenitis, the IRTA1 + MBC population shows a highly preferential usage of the V H genes 3‐7 and 3‐30 (without any obvious peculiarity in their CDR3s), possibly suggesting that a superantigen expressed by Toxoplasma gondii may be involved in the early activation of this B cell subset. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.