Cancer Immune Therapy Edited by G. Stuhler and P. Walden ...

388 Glossary
gp96
See Chaperone.
Graft-versus-host disease (GvHD)
Immune reaction of donor T lymphocytes against the recipient's cells and tissue after
allogeneic bone marrow transplantation (BMT) or hematopoietic stem cell transplantation.
The grafted donor T lymphocytes recognize the host's body as foreign tissue
and mount a T cellular immune reaction. The organs typically most affected are
skin, liver, bowel and lung. MHC molecules can be the trigger and target for GvH reactions
or, in cases where the transplantation was performed with matched MHC,
minor histocompatibility antigens are the focus of the T lymphocyte reactions.
GvHD usually does not affect recipients who have received hematopoietic stem cells
of an identical twin. The GvHD patients usually require immunosuppressive treatments.
While GvHD might cause substantial complications, it is generally accepted
that an antileukemia or antitumor effect of BMT depends on the presence of immune-competent
T lymphocytes in the graft. The issue in BMT, therefore, is often to
achieve a therapeutic GvH reaction against the tumor cells and minimize the pathological
effects on healthy tissues.
Haploidentical cell transplantation
Transplantation of donor stem cells that share half of the co-dominantly expressed
MHC class I and II molecules with the recipient. Haploidentical transplantations are
typically carried out by transferring bone marrow of a parent into a child (see Bone
marrow transplantation).
Heat shock protein (HSP)
See Chaperone.
Helper T cell
CD4 + T lymphocytes with a wide range of factors and processes that provide essential
or supportive aid in the induction, activation and augmentation of effector immune
responses mediated by cytotoxic T lymphocytes or B lymphocytes. T lymphocyte help
for B lymphocyte differentiation is controlled by direct antigen-dependent interaction
of T and B lymphocytes, which implies that the same antigen carries epitopes for
both cells. This epitope linkage requirement is the basis for the hapten-carrier concepts
for the induction of secondary humoral immune responses. In the case of T
lymphocyte help for the induction of CD8 + cytotoxic T lymphocytes, antigen-presenting
cells (APCs) mediate the collaboration of the two T lymphocyte types. The APCs
must present MHC class II- and I-restricted epitopes for the respective T lymphocyte
types. The exact mechanisms of these cellular interactions and the identification of
the factors involved are still under investigation.
hTERT
See Telomerase.