7 research outputs found
Solid Phase-Based Cross-Matching as Solution for Kidney Allograft Recipients Pretreated with Therapeutic Antibodies
In order to select recipients without donor-specific anti-HLA antibodies, the complement-dependent cytotoxicity crossmatch (CDC-CM) was established as the standard procedure about 40 years ago. However, the interpretability of this functional assay strongly depends on the vitality of isolated donors’ lymphocytes. Since the application of therapeutic antibodies for the immunosuppressive regimen falsifies the outcome of the CDC-crossmatch as a result of these antibodies’ complement-activating capacity in the recipients’ sera, we looked for an alternative methodical approach. We here present 27 examples of AB0 blood group-incompatible living kidney allograft recipients who, due to their treatment with the humanized chimeric monoclonal anti-CD20 antibody Rituximab, did not present valid outcomes of CDC-based pretransplant cross-matching. Additionally, four cases of posttransplant cross-matching after living kidney allografting and consequent treatment with the therapeutic anti-CD25 antibody Basiliximab (Simulect) due to acute biopsy-proven rejection episodes are presented and compared regarding CDC- and ELISA-based crossmatch outcomes. In all cases, it became evident that the classical CDC-based crossmatch was completely unfeasible for the detection of donor-specific anti-HLA antibodies, whereas ELISA-based cross-matching not requiring vital cells was not artificially affected. We conclude that ELISA-based cross-matching is a valuable tool to methodically circumvent false positive CDC-based crossmatch results in the presence of therapeutically applied antibodies
Solid phase-based cross-matching for solid organ transplantation: Currently out-of-stock but urgently required for improved allograft outcome
Transplant recipients who have undergone
sensitizing events, such as pregnancy, blood transfusion
or previous transplants, frequently develop antibodies
directed against the highly polymorphous human
leukocyte antigen (HLA)-molecules. These pre-formed,
donor-specific antibodies (DSA) present a high risk of
causing organ failure or even complete loss of the
grafted organ as a consequence of antibody-mediated,
hyper-acute or acute allograft rejection. In order to
detect DSA, the so-called functional complement-
dependent lymphocytotoxicity assay (CDC-XM) was
established about 50 years ago. Although effective in
improving the outcome of solid organ allo-grafting, for
the last ten years this assay has been controversially
discussed due to its low sensitivity and especially
because of its high susceptibility to various artificial
factors, which generally do not yield reliable results. As
a consequence, novel immunochemical test systems
have been developed using ELISA- or bead-based solid
phase assays as replacements for the traditional CDC-
based assays. Because these assays are independent of
single or vital cells, which are frequently not available,
they have provided an additional and alternative
diagnostic approach compared with the traditional
CDC-based and flow-cytometric analyses.
Unfortunately, however, the AMS-ELISA (Antibody
Monitoring System), which was the first system to
become commercially available, was recently
discontinued by the manufacturer after seven years of
successful use. Alternative procedures, such as the
AbCross-ELISA, had to be either considerably
modified, or did not yield reliable results, as in the case
of the Luminex-based assay termed DSA. We draw the
conclusion that due to the unique features and fields of
application reviewed here, the implementation of solid
phase cross-matching still represents an urgent
requirement for any HLA-laboratory’s routine task
General insufficiency of the classical CDC-based crossmatch to detect donor-specific anti-HLA antibodies leading to invalid results under recipients’ medical treatment or underlying diseases
Antibodies directed against HLA antigen of a given donor represent the most prominent cause for hiper-acute and acute rejections. In order to select
recipients without donor-specific antibodies the
complement-dependent cytotoxicity (CDC-) crossmatch
as the standard procedure was established. As a
functional assay it strongly depends on the availability of
isolated donor lymphocytes and in particular on their
vitality. However, due to several diseases or
pharmacological treatment of a given recipient
unexpected “false-positive” results of the CDC-
crossmatch may arise. We here present three groups of
patients which demonstrate the limits of the
conventional crossmatch. 1) Kidney recipients before
living donations exhibited positive CDC-reactions due to
their conditioning using the therapeutical anti-CD20
mAb Rituximab (n=7), routinely used to deplete B-cells,
or the anti-CD25 mAb Basiliximab (n=2) to inhibit the
proliferation of activated T-cells. 2) Recipients suffering
from various leukaemias (n=5) exhibited “positive”
CDC-crossmatches using PBL of the donors, although
formerly these patients had never shown anti-HLA
antibodies. Instead of donor-specific allo-antibodies,
cytostatic agents such as 6-Mercaptopurine led to an
unspecific cell death. 3) Patients projected for post
mortem or living kidney donations (n=44) exhibited
“positive” CDC-crossmatch results which were not in
accordance with their former antibody status and,
partially, with high degrees of HLA-matching. These
implausible results were due to underlying auto-immune false-positive B-cell crossmatches by immune diseases, mainly of the systemic Inmune Complex Type III such a Lupus Erythematosus, mainly leading to false-psitive B- cell crossmatches by
complexes binding to FcÎł
-receptors. In all these 58 cases
the alternatively performed ELISA-based “Antibody
Monitoring System” (AMS-) crossmatch assay was not
artifically affected, suggesting that this assay may be
comprehensively established at least for the cases
described
Induction of Functional Anaphylatoxin C5a Receptors on Hepatocytes by In Vivo Treatment of Rats with IL-6
Serotonin targets inhibitory synapses to induce modulation of network functions
The cellular effects of serotonin (5-HT), a neuromodulator with widespread influences in the central nervous system, have been investigated. Despite detailed knowledge about the molecular biology of cellular signalling, it is not possible to anticipate the responses of neuronal networks to a global action of 5-HT. Heterogeneous expression of various subtypes of serotonin receptors (5-HTR) in a variety of neurons differently equipped with cell-specific transmitter receptors and ion channel assemblies can provoke diverse cellular reactions resulting in various forms of network adjustment and, hence, motor behaviour