Canine pluripotent hematopoietic stem cells and CFU-GM express Ia-like
antigens as recognized by two different class II-specific monoclonal
antibodies
F Schuening, R Storb, S Goehle, J Meyer, T Graham, HJ Deeg and J Pesando
A previous study showed failure of autologous engraftment in lethally
irradiated dogs when marrow was treated before infusion with anti-class II
antibody 7.2 and complement. The current study extended this observation to
a second monoclonal antibody (HB10a) that identifies a different
determinant on Ia-like molecules. These results suggest the presence of
Ia-like antigens on pluripotent hematopoietic stem cells or on "accessory
cells" needed for sustained engraftment to occur. To distinguish between
these two possibilities, stem cell-depleted Ia- positive peripheral blood
leukocytes obtained by discontinuous albumin density gradient were added as
probable source of accessory cells to the marrow inoculum that was depleted
of Ia-positive cells by treatment with antibody 7.2 and complement. Eight
of ten dogs failed to show engraftment, providing further support for the
hypothesis that pluripotent stem cells and not accessory cells were
affected by cytolytic treatment. To provide direct evidence for the
presence of Ia- like antigens on canine pluripotent hematopoietic stem
cells, autologous transplants were performed using 0.7 to 13 X 10(6) Ia
(7.2)- positive marrow cells per kg obtained with the help of fluorescence-
activated cell sorter. Of three evaluable dogs, two showed sustained and
complete engraftment, indicating that Ia-like antigens, as recognized by
anti-class II antibody 7.2, are expressed at least on part of canine
pluripotent hematopoietic stem cells. Concurrent in vitro studies revealed
that canine CFU-GM also expressed Ia-like antigens as recognized by the
class II-specific monoclonal antibodies 7.2 and HB10a.
Volume 69,
Issue 1,
pp. 165-172,
01/01/1987
Copyright © 1987 by The American Society of Hematology
