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R Buelow

Publications and source records attributed to R Buelow.

At least 55 records · Page 3Linked to original sources
PubMed1997

Survival of rat small bowel allografts treated with allotrap 07R.

Previous reports from other investigators demonstrate prolongation of allogeneic heart graft survival and decrease in CTL responses in rats treated with a small synthetic peptide corresponding to residues 75-84 of the human HLA-B7-01 molecule (Allotrap 07R). We wished to determine the efficacy of these peptides in the highly immunogenic ACI > LEW and LEW > ACI small bowel transplant models. Animals were divided into treatment groups: I, none; II, Allotrap (20 mg/kg/day on Days 0-4); III, cyclosporine (CsA; 10 mg/kg/day on Days 0-4); IV, Allotrap + CsA (as in groups II and III); V, Allotrap (40 mg/kg/day every other day on Days -19 to 4); VI, Allotrap + CsA (as in groups III and V); VII, Allotrap + CsA (as in groups III and V, with Allotrap administered intragraft Days 0-4). The animals were sacrificed at the time of graft rejection (defined by dusky, necrotic stoma and increased stomal output). Peripheral blood, spleen, native bowel, and allograft intraepithelial and lamina propria lymphocytes were harvested and mixed lymphocyte culture (MLC) reactivity against self, donor, and third-party splenocytes was assessed. Statistical analysis was performed by ANOVA with Dunnett's t for multiple comparisons against a control as a post hoc test. We found a very slight, but significant prolongation of graft survival in with treatment protocol V for both strain combinations. In addition, MLC response of splenocytes to donor antigen was decreased with combined CsA and Allotrap, but not with Allotrap alone. We conclude that Allotrap decreases response to alloantigens, and slightly, but significantly prolongs graft survival in the hihgly immunogenic small bowel transplant model.

Animals↗
PubMed1997

Characterization of anti-thymoglobulin, anti-Atgam and anti-OKT3 IgG antibodies in human serum with an 11-min ELISA.

Patients treated with OKT3 may become resistant to OKT3 therapy following induction of anti-idiotypic antibodies. Antirabbit or antihorse antibodies following Thymoglobulin (rabbit antithymocyte globulin (ATG) or Atgam (horse ATG) therapy may not similarly inhibit drug efficacy due to an insufficient anti-idiotypic response against the multiple idiotypic specificities of the polyclonal anti-T cell preparations. However, no standardized assay had been developed to monitor antihorse and antirabbit antibodies. To address this issue, we developed three rapid (11-min) and standardized semiquantitative plate enzyme-linked immunoassays (ELISAs) to monitor human serum immunoglobulin-G (IgG) antibodies to Orthoclone OKT3 IgG2a, Atgam and Thymoglobulin. The format was identical for the three assays, with the exception of the immunoglobulin antigen coated on the ELISA plates. As OKT3 is a monoclonal antibody, OKT3 itself is used as the capture antigen. However, for antibody responses against the polyclonal antibody preparations Atgam and Thymoglobulin, it was found that horse IgG and rabbit IgG respectively were equivalent to Atgam and Thymoglobulin as capture antigens. Excellent correlation with a 3.5-h format was demonstrated (r values between 0.986 and 0.845). Specificity was demonstrated by inhibition experiments. Correlations between endpoint titres calculated from serial dilutions and 1:50 dilution OD values were 0.821, 0.983 and 0.937 respectively for the mouse, horse and rabbit assay. High titre sera were selected to assess their ability to block in vitro the binding of OKT3, Thymoglobulin and Atgam to T cells, using flow cytometry. None of the sera containing antihorse (n = 9) or antirabbit (n = 8) antibodies blocked T cell binding of Atgam or Thymoglobulin. In contrast, OKT3 binding was blocked by the four highest titre sera of the 13 anti-OKT3 sera tested. Consequently, prospective monitoring of treated patients using standardized 11-min assays may allow a better assessment of the effect of presensitization to OKT3, Atgam or Thymoglobulin.

Animals↗
PubMed1997

Monoclonal antibody to the HLA class I alpha 3 domain inhibits T cell activation and prolongs cardiac allograft survival in HLA-transgenic mice.

Antibodies recognizing MHC class I molecules expressed on the surface of T cells have been shown to inhibit T cell responses in vitro. These findings suggested that therapy with such an antibody may prevent rejection and promote graft acceptance. We therefore tested the effect of an anti-HLA class I alpha 3 domain antibody (TP25.99) in vivo using transgenic C57BL/6 mice expressing HLA-B2705. Flow cytometric analysis confirmed the binding of TP25.99 to normal human peripheral blood lymphocytes and to mouse spleen cells, bone marrow cells and thymocytes isolated from hemizygous (+/-) transgenic littermates but not from homozygous (-/-) littermates. TP25.99 inhibited OKT-3-induced, but not PMA+ionomycin-induced, proliferation of human peripheral blood lymphocyte as well as anti-CD3 or Con A-induced proliferation of HLA+ mouse T cells. Both intact monoclonal antibody TP25.99 and TP25.99 Fab inhibited T cell proliferation. Reduced proliferation was associated with suppressed production of interleukin-2 as measured by ELISA. The efficacy of TP25.99 Fab in vivo was evaluated in a heart allograft model. Antibody therapy of (H-2h, B2705+) transgenic recipients of allogeneic Balb/c (H-2d) heart grafts prolonged graft survival significantly (MST = 19.8 +/- 6.4, p = 0.003) compared to treated (H-2b, B2705-) (MST = 9.17 +/- 2.2) or untreated (H-2b, B2705+) (MST = 10.0 +/- 2.8) transgenic recipients. This demonstrates that immunomodulation through anti-HLA class I antibody therapy can lead to prolongation of graft survival.

Animals↗
PubMed1996

Targeting of antihapten antibodies to activated T cells via an IL-2-hapten conjugate prolongs cardiac graft survival.

Antihapten antibodies binding to ligand-hapten conjugates are able to mediate complement mediated lysis in vitro. Based on this observation we propose a new in vivo immunotherapy using molecules that combine a low molecular weight hapten binding to antibodies preexisting in serum and a cell specific ligand. The ligand-hapten conjugates are potential cytotoxic drugs which may (1) be specific for a given target cell, (2) be nonimmunogenic, (3) be of low molecular weight, (4) form soluble complexes with preexisting antibodies resulting in prolonged half life of the drug, and (5) induce a potent antibody mediated rejection of target cells. These novel compounds could be useful for the elimination of certain cell subsets involved in allograft rejection, cancers, infectious diseases, etc., without some of the pitfalls of conventional immunotherapies. The feasibility of this approach was demonstrated in an animal model using a compound consisting of one interleukin 2 and one fluorescein molecule (IL-2-FITC). BALB/c mice (H2d) previously immunized and expressing anti-FITC antibodies were transplanted with a fully mismatched C57BL/6 (H2b) heterotopic heart allograft. Untreated controls rejected their graft by day 9 (MSD = 9 +/- 0.7). Mice with preexisting anti-FITC antibodies treated with IL-2-FITC maintained their grafts for 38.7 +/- 7.1 days (P < 0.02). No prolongation of graft survival was observed in immunized animals that were treated with IL-2 alone (MSD = 10 +/- 1.4). Nonimmunized animals treated with IL-2-FITC rejected their grafts on day 9.4 +/- 1.1. This demonstrates that IL-2-FITC therapy specifically prolonged graft survival in animals with circulating anti-FITC antibodies. The data suggest that a ligand/hapten pair can redirect preexisting antihapten antibodies toward target cells in vivo. Such compounds may be developed for human use as alternatives to polyclonal or monoclonal antibody therapy.

Animals↗
PubMed1996

Correlation of ELISA-detected IgG and IgA anti-HLA antibodies in pretransplant sera with renal allograft rejection.

The present study compared the occurrence of rejection episodes during the first twelve posttransplant (Tx) months and the 1-, 2-, and 3-year graft survivals among recipients stratified by the percent panel reactive antibody (% PRA) of pre-Tx sera as detected using either an antihuman globulin determined PRA (AHG-% PRA) or an ELISA methodology detecting IgG reactive against soluble HLA class I antigens (% PRA-STAT). There was a significant correlation between AHG-PRA greater than or equal to 10% and a PRA-STAT greater than or equal to 10% (P<0.001). However, among 200 sera displaying an AHG-PRA greater than or equal to 10% (mean 57 +/- 2l%), only 69% (138/200) displayed a PRA-STAT greater than or equal to 10%. With further study the discrepant finding, of 62 sera that were AHG-PRA greater than or equal to 10% but PRA-STAT <10%, was due to the presence of IgM and/or IgG non-MHC reactivity. In contrast, among 293 sera displaying an AHG-PRA < 100% (mean 3 +/- 2%), 15% (43/293) displayed a PRA-STAT greater than or equal to 10%. There was no correlation between AHG-% PRA and rejection episodes occurring during the first twelve post Tx months. In contrast, however, there was a highly significant correlation between PRA-STAT greater than or equal to 10% and the occurrence of rejection episodes during the first twelve post-Tx months (P < 0.001). Patients with PRA-STAT greater than of equal to 10% experienced a 70% rejection frequency compared with the 35% rejection frequency for patients with PRA-STAT sera < 10% (P<0.001). A significant correlation was observed between the presence of IgG-1 and rejection (P<0.01) but not IgG-subclasses 2, 3, or 4. Of particular interest was the observation in 11 patients that the presence of ELISA-detected IgA anti-HLA class I antigen (ELISA-IgA PRA greater than or equal to 10%) was associated with a significantly reduced rejection risk compared with sera where only PRA-STAT greater than or equal to 10% was present (27% vs. 70% incidence of rejection episodes, P<0.01). Finally, patients displaying pretransplant PRA-STAT results < 10% experienced significantly improved l-, 2-, and 3- year graft survivals of 85% vs. 74%, 82% vs. 70% and 81% vs. 67%, respectively (P<0.01 for each time point), compared with patients displaying PRA-STAT results greater than or equal to 10%. These data suggest that the use of the ELISA methodology to detect IgG reactivity against soluble HLA class I antigens (PRA-STAT) may allow for the determination of a more clinically informative % PRA than the AHG-% PRA. Moreover, the presence of ELISA-detected IgA anti-HLA may act to inhibit rejection mechanisms associated with ELISA-detected IgG anti-HLA greater than or equal to 10%.

Enzyme-Linked Immunosorbent Assay↗
PubMed1996

Immunosuppressive effects of an HLA class I-derived peptide in a rat cardiac allograft model.

B7.75-84, a 10-amino-acid peptide derived from the HLA-B7 molecule, prolongs rat heterotopic cardiac allograft survival time (GST) when used with cyclosporine in the Lewis-to-ACI strain combination. We evaluated the ability of B7.75-84 to prolong GST in other strain combinations without cyclosporine and studied the effect of B7.75-84 on the immune response in the Wistar-Furth (WF)-to-ACI strain combination. GST was markedly prolonged in most low-responder (ACI) recipients but only slightly prolonged in the high-responder (Lewis) recipient. Cytotoxic T lymphocyte (CTL) and helper T lymphocyte (HTL) limiting dilution assays (LDA) were performed 10 days after cardiac allografts from WF donors were placed in ACI recipients treated with B7.75-84. HTL-LDA assays at 10 days posttransplant showed a slight decrease in HTL precursor frequency and a decrease in their IL-2 production in B7.75-84 treated recipients with prolonged GST in response to donor antigen as well as third-party (Lewis) antigen. CTL-LDA assays at day 10 showed no difference in CTL precursor frequency among treated recipients but did show a significant decrease in CTL killing activity against donor cells in recipients with prolonged GST. No significant difference in CTL killing activity was seen against third- party cells. Antibody analysis was performed at day 8 in treated recipients. Serum from B7.75-84-treated recipients with prolonged graft survival generally showed no detectable IgG antibody response against donor MHC class I antigen. All B7.75-84 treated recipients showed a strong IgM response against donor antigen regardless of allograft outcome. Our results suggest that the immunosuppressive effect of B7.75-84 in rats is greater using a low-responder RT1 haplotype. Furthermore, B7.75-84 induces a nonspecific decrease in HTL function while producing a donor-specific decrease in CTL function and a diminished antidonor MHC class I IgG response.

Animals↗
PubMed1996

Pretransplant rejection risk assessment through enzyme-linked immunosorbent assay analysis of anti-HLA class I antibodies.

Soluble HLA enzyme-linked immunosorbent assays (ELISAs) for the detection of anti-HLA class I immunoglobulin G (IgG), IgG1, IgG2, IgG3, IgG4, IgM, and IgA antibodies were developed and used to analyze retrospectively the correlation between pretransplant allosensitization and posttransplant rejection episodes in renal allograft recipients. Enzyme-linked immunosorbent assay plates were coated with 46 different soluble HLA preparations representing 40 different HLA class I antigens. After incubation with a serum specimen, bound antibodies were detected with a peroxidase-conjugated antibody. Serum specimens from 85 patients were analyzed. All patients tested positive by microlymphocytotoxicity (ie, >5% panel-reactive antibody [PRA]). Approximately half (56%) of the patients had experienced one or more rejection episodes within 12 months posttransplantation. Fifty-five patients tested positive by ELISA (total IgG %PRA >10%). A strong correlation between first-year rejection and ELISA-detected anti-HLA class I IgG1 was observed (P = 0.0004). The predictive value for IgG1 and first-year rejection was 77.5%, demonstrating that ELISA results identify patients at high risk of rejecting the transplanted kidney. Anti-HLA class I total IgG detected by ELISA also correlated with first-year rejection episodes (P = 0.04). The presence of anti-HLA class I IgG2, IgG3, IgG4, or IgM was not predictive of first-year rejection episodes. Anticlass I IgA antibodies were only found in combination with anti-class I IgG1 antibodies.

Antibody Specificity↗
PubMed1996

Redirecting circulating antibodies via ligand-hapten conjugates eliminates target cells in vivo.

The elimination of cell populations in vivo often relies on reagents that are self-limiting, are difficult to design and produce or contain highly toxic components. Here we describe a novel immunotherapy using molecules that combine a cell-specific ligand and a hapten binding to preexisting antibodies in serum. The F(ab')2 fragment of a polyclonal anti-thymocyte globulin (ATG) preparation was used as a T-cell-specific ligand, and fluorescein isothiocyanate (FITC), as the hapten. Clearance of ligand-hapten conjugates from the circulation through formation of immune complexes was prevented through controlled synthesis of conjugates so that they contained one F(ab')2 fragment and one FITC molecule. Administration of a single dose of F(ab')2 or F(ab')2ATG-FITC into naive mice had no effect on the number of circulating T cells. In contrast, injection of F(ab')2ATG-FITC into mice with circulating anti-FITC antibodies resulted in the elimination of peripheral T cells. The reduction in cell numbers was equivalent to that obtained with a corresponding dose of intact ATG. Experiments in thymectomized mice demonstrated that the reduction of circulating T cells was due to target-cell elimination and not to immunomodulation or cellular sequestration. The adaptability of the model to other sources of effector antibodies and more useful ligands is discussed.

Animals↗
PubMed1996

Both L- and D-isomers of allotrap 2702 prolong cardiac allograft survival in mice.

BACKGROUND: Peptides derived from a conserved region of the human leukocyte antigen class I heavy chain (a.a. 75-84) have been shown to have immunomodulatory activity. The peptide 07.75-84, derived from HLA-B7, prolonged Lewis 1.W cardiac allograft survival in Lewis 1.A recipients. In combination with cyclosporine A, permanent heart allograft acceptance was induced in the Lewis to ACI donor/recipient combination. In mice, 2702.75-84, derived from HLA-B2702, prolonged the survival of C57B1/6 skin allograft in CBA recipients. In vitro, 2702.75-84 inhibited NK and cytotoxic T cells. To further evaluate the immunomodulatory activity of both L- and D-isoforms of 2702.75-84, we studied their effects in a mouse cardiac allograft model. METHODS: Peptides consisting of L- and D-amino acids were synthesized and administered to CBA (H-2k) recipients of a C57B1/6 (H-2b) cardiac allografts. In addition to peptide monotherapy, combinations of peptide with cyclosporine A and azathioprine were evaluated. Graft survival was monitored by palpation. Breakdown products of 2702.75-84 were identified by a combination of high-performance liquid chromatography and mass spectrometry. RESULTS: Daily administration of 2702.75-84 to CBA (H-2k) recipients of a C57B1/6 (H-2b) cardiac allograft prolonged graft survival to 11.4 +/- 2.6 days compared with 7.5 +/- 1.2 days in untreated control animals (n = 8; p = 0.0003, Mann-Whitney U Test). Other major histocompatibility complex class I-derived peptides including HLA-G.75-84, HLA-07.75-84, HLA-2705.75-84, H-2Kk.75-84, H-2Dk.75-84, H-Kb.75-84, and H-2Db.75-84 had no effect. In combination with a subtherapeutic dose of cyclosporine A (days 0 to 4), 2702.75-84 prolonged graft survival to at least 70 days (five of eight grafts still beating, p = 0.0002) compared with a median graft survival of 14 days in animals that received cyclosporine A monotherapy. Like other peptides consisting of L-amino acids, 2702.75-84 is subject to degradation by serum proteases. Breakdown products of 2702.75-84 were identified by a combination of high-performance liquid chromatography and mass spectrometry. These compounds were found to be inactive when tested in vivo. In contrast to peptides consisting of L-amino acids, peptides consisting of D-amino acids are resistant to proteolytic degradation. When D2702.75-84 was administered to graft recipients at 5 to 10 mg/kg/day (days 0 to 10), graft survival was prolonged to more than 50 days (5 of 13 grafts still beating, p = 0.0001). In combination with azathioprine, administration of D2702.75-84 induced graft acceptance (> 100 days) in 100% of animals (all grafts still beating). CONCLUSIONS: This study shows that administration of 2702.75-84 consisting of L- or D-amino acids will prolong graft survival in mice. In addition, the data suggest that the D2702 isomer is more potent than the L-isomer in vivo and may allow reduced dosage or frequency of administration.

Adjuvants, Immunologic↗
PubMed1995

Soluble HLA antigens and ELISA--a new technology for crossmatch testing.

A soluble HLA ELISA for the detection of donor specific anti-HLA class I IgG antibodies was developed and compared with microlymphocytotoxicity. Donor sHLA was prepared from donor blood or purified blood lymphocytes and captured onto monoclonal antibody coated ELISA plates. After incubation of captured HLA with test serum, bound IgG antibodies were detected using a peroxidase-conjugated anti-human IgG antibody. Serum samples from patients on waiting lists to receive kidney transplants were tested by lymphocytotoxicity (AHG protocol) and/or sHLA ELISA in four different laboratories using HLA preparations from eight organ donors. Concordant crossmatch results were obtained for 854 (99%) of 864 ELISA crossmatches. In contrast, concordant results were obtained for 234 (91%) of 256 lymphocytotoxicity crossmatches. Interlaboratory reproducibility of ELISA results was 99%. In contrast, interlaboratory reproducibility of lymphocytotoxicity assay results was 78%. Endpoint titrations of serum specimens containing anti-HLA antibodies demonstrated equivalent sensitivity of ELISA and AHG lymphocytotoxicity crossmatch and similar sensitivity of ELISA and flow cytometry crossmatch. Specimens tested positive by lymphocytotoxicity without DTT treatment but negative with DTT treatment were tested negative by ELISA. Comparison of lymphocytotoxicity and ELISA crossmatch results showed an agreement of 94%. This demonstrates that detection of anti-donor HLA class I antibodies by ELISA is a reliable alternative to microlymphocytotoxicity testing.

Enzyme-Linked Immunosorbent Assay↗
PubMed1995

A synthetic dimeric HLA class I peptide inhibits T cell activity in vitro and prolongs allogeneic heart graft survival in a mouse model.

A peptide derived from the alpha 1 domain of the human HLA class I heavy chain (amino acids 75-84; B2702.75-84) has been shown to inhibit human cytotoxic T and NK cell activity in a non-allele-restricted manner. In vivo, this peptide prolonged skin allograft survival in a murine model. Here we demonstrate prolongation of heart allograft survival in mice and extend the characterization of the immunomodulatory activity of B2702.75-84. Similar to what has been observed with retrovirus-derived peptides, the inhibitory capability of this peptide was increased when bound to a carrier protein. An increased immunomodulatory activity was also observed with the dimeric peptide B2702.84-75-75-84 or the multimeric B2702.75-84.MAP. This peptide not only inhibited cytotoxic T and NK cells but also anti-CD3-induced T cell proliferation as well as a mixed lymphocyte reaction (MLR). Flow cytometric analysis of T cells harvested from anti-CD3-stimulated spleen cell culture in the presence of B2702.84-75-75-84 showed decreased expression of activation markers (CD25, ICAM-1, Pgp-1, CD69) compared with untreated control cultures. The superior activity of B2702.84-75-75-84 could also be demonstrated in vivo. Administration of B2702.84-75-75-84 prolonged the survival of B6 (H2b) hearts in CBA (H2k) recipients to 15 +/- 2.7 (P = 0.0002 vs. control) days compared with 11.4 +/- 2.6 (P = 0.01) days in B2702.75-84 treated animals and 7.5 +/- 1.1 days in untreated controls. Administration of control peptides had no significant effect on allograft survival. In combination with a subtherapeutic dose of cyclosporine, B2702.75-84 induced long-term graft survival in 60% of recipients.

Amino Acid Sequence↗
PubMed1995

Prolongation of skin allograft survival in mice following administration of ALLOTRAP.

Recently, Clayberger et al. demonstrated that ALLOTRAP, small synthetic peptides derived from a conserved region of the alpha 1 helix of certain HLA class I molecules, inhibited human CTL responses in vitro. In rats, ALLOTRAP 07 therapy combined with a subtherapeutic dose of cyclosporine led to the permanent acceptance of heart allografts. In the present study, the effect of ALLOTRAP on the survival of skin allografts in mice was studied. The tail skin of male C57B1/6 (H-2b) mice was grafted on the back of male CBA (H-2k) recipients. In untreated animals, the skin graft was rejected after 11.6 +/- 1.13 days (MST +/- SD). Cyclosporine administered orally for 5 days after transplantation prolonged graft survival to 13.1 +/- 2.13 days. ALLOTRAP 2702 prolonged graft survival to 16.57 +/- 2.15 days when administered orally for five days posttransplantation and to 18.86 +/- 0.38 when administered intraperitoneally until rejection. Thus, ALLOTRAP peptides derived from human MHC class I sequences, in addition to inhibiting human T cell responses in vitro, also prolong allograft survival in rats and mice.

Administration, Oral↗
PubMed1995

Detection of panel-reactive anti-HLA class I antibodies by enzyme-linked immunosorbent assay or lymphocytotoxicity. Results of a blinded, controlled multicenter study.

A soluble HLA ELISA for the detection of anti-HLA class I IgG antibodies was developed and compared to complement-dependent microlymphocytotoxicity. ELISA plates were coated with a panel of sHLA class I antigens isolated from the culture supernatants of 46 different EBV-transformed phenotyped B-cell lines. After the incubation of the coated plates with test serum, bound antibodies were detected using a peroxidase-conjugated anti-human IgG antibody. Absorbance was read using an ELISA plate reader and assay results were analyzed by computer. Antibody specificities were determined by Fisher's exact test tail analysis. The reproducibility of ELISA assay results was evaluated in a blinded, controlled multicenter study. A total of 102 serum specimens from patients on waiting lists to receive kidney transplants were tested five times by ELISA in five different laboratories. The correlation coefficients (r) of %PRA values determined by ELISA ranged from 0.89 to 0.96, and the average agreement on qualitative assay results (antibody positive vs antibody negative) was 98%. Endpoint titration of several serum specimens demonstrated equivalent sensitivity of ELISA and microlymphocytotoxicity (using the anti-globulin antibody protocol). Most of the antibody specificities determined by ELISA were in agreement with specificities determined by microlymphocytotoxicity. To evaluate the correlation of ELISA and microlymphocytotoxicity (CDC) assay results the same 102 specimens were tested six times by CDC in five different laboratories. The interlaboratory correlation coefficient (r) of %PRA values determined by microlymphocytotoxicity ranged from 0.57 to 0.94, and the average agreement on qualitative assay results was 85%. A comparison of ELISA with microlymphocytotoxicity was performed using consensus microlymphocytotoxicity results. This showed a high correlation (r = 0.81) of %PRA values determined by ELISA and microlymphocytotoxicity. This demonstrates that the detection of anti-HLA class I antibodies by soluble HLA ELISA is a reliable alternative to microlymphocytotoxicity testing.

Antibody Specificity↗
PubMed1994

Detergent-enhanced dissociation of endogenous peptides from PI-DRB1*0401.

A variety of detergents have been shown to catalyze the dissociation of bound peptides from a soluble from of DRB1*0401. By using a class II molecule lacking the hydrophobic transmembrane region, the need for solubilizing the transmembrane protein was removed and enabled the specific interaction between the class II protein and the amphiphile to be identified. The presence of detergent increased the rate of association of added peptide and the percent occupancy of the receptor, presumably because the dissociation of endogenous peptide was the rate-limiting step in binding. The data help explain the differences reported between peptide binding to class II proteins on the surface of cells and binding to class II proteins solubilized in detergent. The interaction did not correlate with the critical micellar concentration of the detergent nor were all amphiphilic structures equally effective, consistent with a specific interaction between the amphiphile and the MHC class II protein. Of the eight detergents examined, octyl glucoside was the most efficient. These experiments did not distinguish between an allosteric mechanism or direct competition with the peptide for binding.

Amino Acid Sequence↗
PubMed1994

Typing of a panel of soluble HLA class I antigens by enzyme-linked immunosorbent assay.

Two ELISA assays were developed to test the reactivity of soluble sHLAs with anti-HLA class I mAbs of IgG or IgM isotype. A panel of 40 different alleles of sHLA antigens was produced using 57 lymphoblastoid B-cell lines, which had been generated from class-I-phenotyped PBLs. Using 14 mAbs, the expression of 13 different sHLA antigens (sHLA-A2, -A3, -A11, -A24, -A29, -B7, -B8, -B13, -B14, -B27, -B44, -B57, and -B58) by 43 different cell lines was confirmed. In addition, the expected absence of these alleles from the culture supernatant of 11 cell lines was confirmed. Cross-reactivities of mAbs observed by microlymphocytotoxicity assays were also detected by ELISA. The results of this extensive analysis confirmed previous results demonstrating that sHLA class I typing by ELISA correlated with HLA class I cell typing by microlymphocytotoxicity [1-3]. Furthermore, additional information about the fine specificities of two mAbs was obtained. An anti-B27/44 IgM mAb appeared to react only with sHLA-B44 but not with sHLA-B27; mAb CR11-351, previously reported to react with HLA-A2, 28, bound also to sHLA-A1, -3, -11, and -A24.

Alleles↗