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Immunohistological Expression of Interleukin 16 in Human Tonsils
Matthias F. Kramer, MD;
Brigitte Mack;
Gerd Rasp, MD
Arch Otolaryngol Head Neck Surg. 2001;127:1120-1125.
Background Interleukin 16 (IL-16) acts highly chemotactic on CD4-bearing cells.
Besides chemotaxis, IL-16 has numerous immunomodulatory effects, and not only
on T cells.
Objective To determine IL-16 expression in human tonsils.
Methods Tonsillar follicles were immunohistologically characterized to elicit
a possible cellular source of IL-16 expression.
Results The mantle zone of immature and mature B cells was CD22 immunoreactive
(ir), whereas the germinal center of activated B cells was CD23-ir. Plasma
cells that were CD38-ir were observed extrafollicularly beneath the epithelium
and within the germinal center. T cells were found most frequently in the
extrafollicular space, with a majority of CD4 cells. CD68-ir macrophages were
predominantly found within the germinal center. Immunostaining of anti–IL-16
revealed strong cytoplasmatic reactivity of extrafollicular cells and of cells
at the outer rim of the mantle zone. Numerous cells adherent to the stratified
squamous epithelium were IL-16-ir as well. Double immunostaining identified
CD4+ T cells as the major cellular source of IL-16 expression.
Furthermore, a population of CD22+ B cells at the outer rim of
the mantle zone expressed IL-16 as well.
Conclusions Interleukin 16 was mainly expressed in a typical CD4-like pattern in
human tonsils. Our data strongly suggest that CD4+ lymphocytes
constitute the major cellular source for IL-16. We hypothesize that the double-immunostained
CD4-ir and IL-16-ir cells represent activated T cells. Because CD22+ B cells at the outer rim of the mantle zone expressed IL-16 as well,
we conclude that this area might constitute the locus of IL-16–mediated
B-cell differentiation.
From the Department of Oto-Rhino-Laryngology/Head and Neck Surgery,
Ludwig-Maximilians-University, Munich, Germany.
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Arch Otolaryngol Head Neck Surg. 2001;127(9):1146-1148.
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