Phenotype and function of lamina propria T lymphocytes.
Lamina propria T cells have a low expression of the CD45RA antigen and a high expression of the CD45RO antigen. This phenotype is characteristic for memory T cells (table 2). In addition, T cells in the effector compartment of the mucosa bear surface antigens which are very rarely found in other sites of the immune system. Intestinal T cells also express functional IL-2 receptors and IL-2 receptor alpha chain mRNA, and are able to synthesize high amounts of IL-2. However, another marker of memory T cells, CD29, is not expressed in high density in the lamina propria indicating that lamina propria T cells differ from 'classical' memory T cells. This is supported by functional studies in nonhuman primates infected rectally with C. trachomatis which show that lamina propria T cells do not proliferate after stimulation with antigen but rather provide helper function for immunoglobulin synthesis (table 2). The intestinal lamina propria therefore contains highly specialized T cells which have a distinctive phenotype and are activated. Functionally these T cells can be characterized as differentiated effector lymphocytes which respond to triggering the antigen-specific T cell receptor by secreting helper factors for B cells. This concept is supported by recent studies showing that the pattern of lymphokines produced by lamina propria T cells and the responsiveness to certain lymphokines differ from those of other lymphocyte populations [25]. Lamina propria T cells thus represent a subset of memory T cells with a unique maturational state.
Zeitz
M
M
Department of Gastroenterology, Free University of Berlin, FRG.
Schieferdecker
H L
HL
Ullrich
R
R
Jahn
H U
HU
James
S P
SP
Riecken
E O
EO
D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte; D006801:Humans; D007156:Immunologic Memory; D007413:Intestinal Mucosa / Q000166:cytology / Q000276:immunology*; D008213:Lymphocyte Activation; D010641:Phenotype; D011948:Receptors, Antigen, T-Cell; D013601:T-Lymphocytes / Q000276:immunology*
D000945:Antigens, Differentiation, T-Lymphocyte; D011948:Receptors, Antigen, T-Cell