M. Barda-saad et al., Adhesion molecules involved in the interactions between early T cells and mesenchymal bone marrow stromal cells, EXP HEMATOL, 27(5), 1999, pp. 834-844
We previously reported that among the various thymic lymphocyte subpopulati
ons, the immature T cells preferentially adhere to mesenchymal bone marrow
stroma, In the present study we examined the interactions between phenotypi
cally defined populations of early T cells and stromal cell lines, The imma
ture T cells segregated into two subpopulations according to their adhesive
capacity. Whereas the majority of the adherent CD4(-)CD8(-) T cells were d
evoid of CD3/TCR alpha beta, most of the nonadherent CD4(-)CD8(-) T cells e
xpressed this receptor complex. The adhesion of T cells to bone marrow stro
ma almost entirely was accounted for by CD49d and CD90, whereas that of adh
erent CD4(-)CD8 cells also was dependent on CD44, CD62L, and CD117 receptor
. Blocking antibody combinations failed to reduce the adherence of these ea
rly T cells to less than 50% that of the control, On the other hand, the ad
hesion of unselected thymocytes to the stroma was reduced by 80%, using the
same blocking antibodies. Therefore, the participation of additional molec
ules in the adhesion of early T cells to mesenchymal stroma is implicated.
Comparison between the interaction of T cells with bone marrow mesenchymal
or with thymus-derived epithelial stroma indicated that T cells utilize a s
elected set of adhesion molecules under each situation. Although CD49d and
CD90 participated in both cases, CD11a, CD18, and CD2 receptors played a do
minant role in the adhesion of T cells to thymic epithelium only, This stud
y may point to a role of mesenchymal stroma in the regulation of early T-ce
ll lymphopoiesis in the bone marrow. (C) 1999 International Society for Exp
erimental Hematology. Published by Elsevier Science Inc.