Biomedical subjects
Publications and source records attributed to W Müller-Ruchholtz.
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We investigated the biochemistry of naturally occurring major histocompatibility complex (MHC) class I molecules in human serum and established a quantitative enzyme-linked immunoassay (ELISA) to determine soluble human leukocyte antigen (HLA) concentration. Peptides of 46, 40, 37, 35, and 12 kDa were isolated on affinity chromatography columns using two monoclonal antibodies (MoAbs), the anti-heavy chain W6/32 and the anti-beta 2-microglobulin BBM. 1. These peptides were confirmed on Western blots by the HC-10 MoAb, which binds a monomorphic epitope on denatured heavy chains. In detergent-binding experiments, only the 46-kDa peptide could be isolated from solubilized cell membranes. No quantitative differences between serum and plasma HLAs of the same individual were measured. Soluble HLA expression in 12 renal graft recipients was measured over 1-3 mo posttransplantation. A highly significant increase of 50%-100% was noted during rejection episodes. Clinical signs of rejection were accompanied by poor renal function, including elevated creatinine values. After the crises had been managed, class I levels normalized to 0.3-1.5 micrograms/ml, which is the range in healthy persons. Patients who showed no rejection crises maintained constant levels within the period of study. We anticipate the application of soluble HLA measurement in clinical practice as a noninvasive graft monitor.
An effective prophylaxis of graft-versus-host reaction in clinical bone marrow transplantation can be achieved by T depletion of the graft. However, this kind of graft manipulation is accompanied by a strongly increased incidence of graft rejection. In order to eliminate this hazardous complication we studied the possibility of preventing rejection of a BM graft by reducing its immunogenicity. In this report we demonstrate that the capacity of human BM cells to induce proliferation of allogeneic T cells is strongly reduced after treatment with the antilymphocyte/antimonocyte monoclonal antibody K31+ rabbit complement (C), indicating a reduced immunogenicity of the BM cells. On the other hand, the allostimulatory capacity of BM treated with clinically established T-depleting MoAbs, including the more broadly reactive CAMPATH-1, was not or only slightly reduced. MHC class II induction on BM cells with human recombinant gamma-interferon did not restore the allostimulatory capacity reduced by K31+C. Exogenous IL-1 partially inhibited the K31-mediated reduction of allostimulatory capacity. Reduction of the allostimulatory capacity of BM cells with K31+C correlated with a reduction of their capacity to support mitogen-induced proliferation of purified autologous T cells, indicating the absence of accessory functions. Addition of autologous peripheral adherent cells to K31+C treated BM restored its accessory function as well as its allostimulatory capacity. Labeling studies confirmed that accessory cells are critical for the described K31-mediated effects. We conclude that depletion of accessory cells in addition to lymphocytes with K31+C strongly reduces the immunogenicity of a BM graft, may help prevent graft rejection, and may serve as a model for preconditioning other organ grafts.
Soluble class I molecules were immunoprecipitated from human sweat and serum using the BB7.7 monoclonal antibody (mAb) coupled to immunomagnetic beads. Molecules were analysed biochemically on SDS-PAGE gels and finally by ID-isoelectric-focusing (IEF). Serum- and sweat-HLA IEF-band patterns of the same individual were fully identical, showing that HLA excreted in sweat possess polymorphic structures like those in serum. Quantitatively, we used a highly sensitive competitive enzyme-linked immunosorbent (ELISA) assay to determine soluble class I concentrations. The first group was that of non-HLA-A9 and -Bw62 sera, which were found to contain HLA levels with a mean concentration of 0.82 +/- 0.63 microgram/ml (n = 44). However, sera that were HLA-A23 or -24 (splits of HLA-A9) contained higher levels, with a mean of 3.2 +/- 0.94 microgram/ml (n = 20). Similarly, HLA-Bw62 individuals had a higher mean of 2.05 +/- 0.65 micrograms/ml (n = 10). The difference of the HLA-A9 group to the first group was statistically highly significant, P less than 0.0001, and that of the HLA-Bw62 to the first was also significant, P less than 0.004. Individuals who were both HLA-A9 and -Bw62 (n = 5) did not express significantly higher levels than those who only had one of these specificities. Sweat HLA levels had a mean of 0.42 +/- 0.4 microgram/ml (n = 10). These results show for the first time that soluble class I peptides are excreted in relatively high concentrations in sweat and possess polymorphic structures identical to those of serum HLA and that serum HLA levels are allotype dependent.
The immunogenicity of an industrially produced bacterial food protein (single cell protein, SCP) was analyzed in a comparative study. SCP, casein and ovalbumin were injected into or fed to rats. The systemic response was tested in vitro with a lymphocyte transformation test and in vivo with a footpad swelling assay. Feeding of casein induced cell-mediated reactivity against casein, while feeding of SCP or ovalbumin had no effect. One injection of casein led to sensitization compared with three injections of SCP. Prior feeding of SCP did not abrogate the response to injected SCP. The footpad swelling test is suggested as a particularly effective model for helping to determine the immunological risk of foodstuffs to man.
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The human monoclonal antibody Ha6D3 of the IgM type was used to stain malignant lymphoma cells from peripheral blood in flow cytometry and from cryosections of lymph nodes using the immunoperoxidase technique. It was found to react with peripheral white blood cells of all 12 cases of leukaemia and with lymph node cells of seven out of 11 B cell lymphomas and with the one T cell lymphoma tested so far. For in vivo experiments a batch of 70 mg Ha6D3 was purified and 6 mg Ha6D3 was injected intravenously into a chimpanzee with time intervals of 10 months and 1 month. The side effects observed were shivering, some muscular spasms and variations in the heart frequency. A decrease of lymphocytes of more than 50% was documented by haematogram analysis. The flow cytometry data showed that the Ha6D3 antigen does not modulate. Even after three repeated injections applied in a time interval of several months no immune response to Ha6D3 could be detected in vivo or in vitro. Based on these data we suggest that Ha6D3 may become a candidate for the treatment of certain leukaemias in vivo.
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For the study of the epitope distribution on HLA class I molecules, blocking studies were carried out with a competitive radioimmuno assay using 3H labelled monoclonal antibodies (MAbs) against various HLA epitopes. The results were discussed with the help of known HLA amino acid sequences, and the positions of the following epitopes were suggested: A2/Aw69; A2/28; A2/11/25/26/28/29/30/31/Aw33/34; A25/32; Bw4; B7/Bw22,42; Bw6.