Antilymphocytic antibodies and marrow transplantation. XII. Suppression of
graft-versus-host disease by T-cell-modulating and depleting antimouse CD3
antibody is most effective when preinjected in the marrow recipient
J Mysliwietz and S Thierfelder
Institut fur Immunologie der GSF-Forschungszentrum fur Umwelt und
Gesundheit, GmbH, Munich, Germany.
A hamster antimouse CD3 monoclonal antibody (MoAb) opened the way to
experimental studies on the suppression of allograft rejection and
cytokine-related morbidity after treatment with antibodies modulating the
CD3/T-cell receptor complex (CD3/TCR). Because earlier attempts to suppress
graft-versus-host disease (GVHD) in patients by in vitro treatment of donor
marrow with anti-CD3 MoAb had remained inconclusive, we used a rat IgG2b
antimouse CD3 MoAb (17A2) with fewer side effects to analyze suppression of
GVHD in the mouse model. Detailed phenotyping of blood, spleen, and
lymphnode T cells after the injection of 400 micrograms 17A2 in C57BL/6
mice showed 60% CD3 downmodulation and 50% T- cell depletion for spleen
cells. Injection of these spleen cells, together with bone marrow cells, in
fully mismatched preirradiated CBA mice delayed GVHD by only 6 days. Ex
vivo treatment of donor cells with 17A2 was not effective. In contrast,
conditioning of marrow recipients with a single injection of 17A2 delayed
50% GVHD mortality by 100 days and prevented GVHD altogether after
prolonged treatment, with survivors showing complete chimerism and specific
transplantation tolerance. This difference in antibody effect contrasts
with earlier experiences with nonmodulating but more strongly
T-cell-depleting MoAbs of the same isotype, which prevent GVHD no matter
whether applied in vitro or injected into donor or recipient mice. Our data
indicate that CD3/TCR reexpression in marrow recipients with no circulating
17A2 is the reason why ex vivo donor cell treatment with anti-CD3 MoAb is
comparatively ineffective. Our data, which allow separate evaluation of
cell-depleting and cell-modulating antibody activity, help to explain
previous clinical failure to suppress GVHD and provide evidence in favor of
conditioning the marrow recipient with anti-CD3 MoAb as a therapeutic
alternative.
Volume 80,
Issue 10,
pp. 2661-2667,
11/15/1992
Copyright © 1992 by The American Society of Hematology