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Biomedical subjects

P R McConnachie

Publications and source records attributed to P R McConnachie.

At least 19 recordsLinked to original sources
PubMed1992

Inhibition of immunoglobulin (Ig)G-Fc-mediated cytotoxicity by seminal plasma IgG-Fc receptor III antigens.

OBJECTIVE: To determine if the presence of soluble immunoglobulin (Ig)G-Fc receptor III (Fc gamma RIII) antigens in human seminal plasma interfere with IgG-Fc-mediated effector functions. DESIGN: An antibody-dependent cellular cytotoxicity (ADCC) assay was used as a model for IgG-Fc-mediated effector functions. Human red blood cells (RBC), labeled with 51Cr were sensitized with rabbit anti-RBC and used as targets for peripheral blood leukocyte (PBL) effector cells. Cytotoxicity was measured by assessing the release of 51Cr from RBC. INTERVENTIONS: (1) Seminal plasma was added at different concentrations to the ADCC, and inhibitory effects were measured. (2) The level of seminal plasma interaction in ADCC was studied by comparing ADCC results in the presence and absence of seminal plasma with findings of target and effector cells that had been preincubated with seminal plasma. (3) The role of seminal plasma Fc gamma RIII in inhibiting ADCC was studied by coincubating seminal plasma with monoclonal antibodies (MAs) Leu 11b that block Fc gamma RIII binding sites. Two isotype-matched MA controls were used at identical concentrations. RESULTS: (1) Seminal plasma dose dependently inhibits ADCC. (2) Seminal plasma inhibition of ADCC occurs at the level of IgG-Fc interaction with effector cell Fc gamma receptors. (3) Inhibitory effects of seminal plasma on ADCC can be specifically blocked by coincubating seminal plasma with MAs Leu 11b that block Fc gamma RIII binding sites. CONCLUSIONS: Seminal plasma Fc gamma RIII antigens interfere with IgG-Fc-mediated effector functions. This mechanism could play a beneficial role in controlling potentially harmful antipaternal immune responses.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1991

Lymphocytic interstitial pneumonitis in autoimmune thyroid disease.

Four patients are described who were found to have autoimmune thyroid disease associated with lymphocytic interstitial pneumonitis. The patients were not receiving any medications known to cause lymphocytic interstitial pneumonitis. Their response to steroid therapy and the relapse of their clinical symptoms after steroid withdrawal support an underlying immunologic dysfunction. It is proposed that lymphocytic interstitial pneumonitis may be yet another manifestation of immune dysfunction in autoimmune thyroid disease.

Adult↗
PubMed1987

Characterization of immunoglobulin class and subclass responses in secondary aborter sera.

Sera from secondary (2 degrees) aborters exhibit persistent, high-titred cytotoxicity against paternal as well as HLA dissimilar non-paternal lymphocytes. The majority of antipaternal complement-dependent cytotoxicity (CDC) and complement-independent antibody dependent cellular cytotoxicity (ADCC) was recovered in IgG enriched fractions following ion-exchange chromatography of 2 degrees aborter sera. The IgG subclasses mediating antipaternal reactivity were determined using murine anti-human IgG subclass specific monoclonal antibodies and Protein A affinity chromatography (SPA). Inhibition of paternal CDC by the anti-subclass reagents showed 75-90% of the reactivity mediated by maternal IgG1 antibodies. Anti-IgG3 inhibited 15-30% whereas anti-IgG2 produced little inhibition. SPA chromatography of 2 degrees aborter IgG supported the monoclonal antibody results in that greater than 80% of the CDC activity was recovered in the IgG1, 2, and 4 containing eluate and 20% was found in the IgG3 enriched effluent. Although the anti-IgG subclass specific monoclonals did not inhibit antipaternal ADCC, IgG3 did not appear to mediate this cytotoxicity as the ADCC was recovered in the eluate and not the effluent following SPA chromatography of 2 degrees aborter IgG enriched serum fractions. These data indicate that the humoral antipaternal and polyspecific CDC immune reactivities of 2 degrees aborters are due to the production of IgG1 and IgG3 antibodies.

Abortion, Habitual↗
PubMed1986

Differences in immunoglobulin subclasses between dye exclusion and 51Cr release complement-dependent lymphocytotoxicity assays.

Paradoxical differences previously noted between lymphocytotoxicity detected by dye exclusion at room temperature (CDCE) or by 51Cr release (CDC51Cr) at 37 degrees C in maternal antipaternal complement-dependent lymphocytotoxicity have suggested that CDCE and CDC51Cr at 37 degrees C, but not at 20 degrees C, may detect different immunological antibody-antigen interactions. Reactions in the two test systems against the same target cells were compared in sera from known immune dialysis patients, secondary aborting women, and refractory platelet recipients before and after heat treatment of sera, absorption with solid-phase heparin, anti-light-chain augmentation, and the addition of murine monoclonal anti-IgG subclass antibodies. The results demonstrate significant differences between the two tests using the same target and sera. Further, the results imply the presence of an inhibitor and an inhibitor of inhibitor in sera. The involvement of different immunoglobulin subclasses was shown in the two tests. These data demonstrate the necessity for further study of the nature of the differences in the mechanisms of these clinically important antibody-detecting systems.

Abortion, Spontaneous↗
PubMed1986

Inhibitors of complement-mediated cytotoxicity in normal and secondary aborter sera.

Sera from patients with secondary (2 degrees) spontaneous abortions contain complement-dependent cytotoxic (CDC) antibodies with specificity for paternal lymphocytes. These lymphocytotoxins are not anti-HLA (human lymphocyte antigen) as shown by their polyspecificity on HLA select cell panels and by their removal following absorption with HLA-negative trophoblast membranes. They are predominantly IgG and have been designated as trophoblast-lymphocyte cross-reactive (TLX) antibodies. Normal and homologous 2 degrees aborter sera contain a CDC inhibitor that does not bind to paternal cells and must be present when complement is added to antibody. The inhibitor does not manifest anticomplement effects and appears to be species specific. Inhibitory capacity is increased by heating (56 degrees C for 30 min) and by absorption with heparin. When chromatographed on G-200 Sephadex, inhibitor appears in the void volume, suggesting a molecular weight of more than 250,000. It can be isolated from diethylaminoethyl cellulose into an euglobulin fraction that does not contain IgG, but does contain IgM, though no studies indicate the inhibitor to be IgM. We suggest that the inhibitor is under the control of a regulator molecule, probably an inhibitor-of-inhibitor, and that in 2 degrees aborter sera the equilibrium is unbalanced between antibody, inhibitor, and regulator.

Abortion, Habitual↗
PubMed1985

Restricted effector cell function in ADCC.

Human effector cell function in ADCC reactions was studied as a result of observations showing discrepant ADCC reactivities among different effector cell populations. Effector cells prepared from ten blood donors were tested individually and as a pool against a battery of nine antisera-target cell combinations in an 11-x-9 matrix. The results identified individuals with weak, intermediate, and strong effector cell functions; however, there was a wide range of ADCC reactivity by each person's effector cells against the nine targets. No single antibody-target cell combination was consistently subjected to the least kill or greatest kill by the different effector cell preparations. Pooled effector cell responses were found to be weaker than expected. There was no relationship of age or sex with effector cell function, but a trend was noted for strong and weak reactions to be associated with HLA-DR7 and DR1, respectively. Neither the sharing of HLA antigens between effector and target cells nor self ADCC reactivity could account for the variations in effector cell function. Exploratory principal components factor analysis suggested that recognition of antibody-target cell combinations by effector cells was represented by three major groupings. These data collectively indicate the existence of an allorestrictive Fc receptor recognition step in ADCC responses.

Adult↗
PubMed1984

Maternal antipaternal immunity in couples predisposed to repeated pregnancy losses.

Maternal antipaternal immunity was compared between a group of 12 couples with normal reproductive histories and a group of 13 couples with obstetrical histories of more than one consecutive stillbirth or repeated pregnancy loss subsequent to having had successfully carried to term. Couples were studied for maternal-paternal HLA antigen sharing and for maternal antihusband immunity in tests detecting both complement dependent and independent antibodies as well as in an assay measuring direct cell-mediated cytotoxicity. There was no significant difference in the proportion of HLA antigen sharing between these two groups; however, the women in the pregnancy loss group demonstrated significantly more antipaternal immunity than their normal childbearing counterparts and more than previously described for aborting couples who share HLA antigens. Screening of the cytotoxic sera on a well characterized cell panel failed to reveal alloreactivity patterns consistent with paternal HLA antigen profiles. These data demonstrate that certain women who suffer recurrent pregnancy losses can mount vigorous immune responses to paternal lymphocyte antigens. We propose that the appearance of such lymphocytotoxins represents inappropriate maternal immune responses to fetal extraembryonic antigens that may subsequently result in fetal demise.

Abortion, Habitual↗
PubMed1984

Clinical, immunologic, and genetic definitions of primary and secondary recurrent spontaneous abortions.

Fifty couples with repeated pregnancy failures were grouped by clinical history as being primary (no children) or secondary (abortions subsequent to having children or stillbirths) aborters. Human leukocyte antigen (HLA) sharing between husband and wife and maternal antipaternal immunity were studied in both groups. Analyses showed significantly more HLA-A, B, and DR locus antigens shared in the primary abortion group than in the secondary abortion group (P = 0.01). The number of couples sharing two to five HLA antigens was higher for those couples with primary abortions than for secondary abortions (P = 0.009). Antipaternal immunity as measured by visual complement-dependent lymphocytotoxicity (CDCE), by 51Cr release (CDC51Cr), and by complement-independent, antibody-dependent cell-mediated cytotoxic (ADCC) assays was different between the two groups. CDCE was not present in the primary aborters' sera but was found in 13 of the 15 secondary aborters' sera (P = 0.0001). Similarly, ADCC was not apparent in primary aborters but was present in 14 of the 15 secondary aborters (P = 0.0001). CDC51Cr was detected in 3 of the 11 primary aborters and in 13 of the 15 secondary aborters (P = 0.008). Such differences in HLA sharing and immune reactivities between these two groups strengthen the idea that either inadequate or inappropriately vigorous maternal antipaternal immunity can be related to spontaneous abortions. These results uphold a central role for immunology in human reproduction and provide further support for the use of immunotherapy to prevent pregnancy losses in certain abortion-prone women.

Abortion, Habitual↗
PubMed1983

HLA antigens and necrobiosis lipoidica diabeticorum--a comparison between insulin-dependent diabetics with and without necrobiosis.

To investigate whether HLA-A, -B, -C, and -DR alloantigen frequencies are different in diabetic patients with and without necrobiosis lipoidica diabeticorum we studied 37 insulin-dependent (Type I) diabetics, 15 with and 22 without necrobiosis, and 96 normal control subjects. Compared to controls Type I diabetics had increased frequencies of B8, CW3, and DR4 and decreased frequencies of DR5 and DR7. Diabetics with necrobiosis differed from diabetics without necrobiosis only in that HLA-A2 was significantly less frequent in patients with necrobiosis. It is suggested that the lack of major differences between patients with and without necrobiosis argues in favour of the role of metabolic and/or vascular rather than genetic factors in the aetiology of necrobiosis.

Adult↗
PubMed1979

False positive 51Cr release tests during post-transplant immunological monitoring due to recipient serum radioactive contamination.

The occurrence of false positive 51Cr release test results in post-transplant immunological monitoring of human kidney graft recipients due to 131I carryover from renograms is described. False positivity was detected in 7 instances in 4 recipients, and suspected in 12 instances in 7 recipients, in a series of 46 consecutive transplant recipients. Technical methods and controls to detect and prevent such false positivity are described.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1975

Serotyping for MLC gene products: I. Presumptive evidence that ABCIL may detect MLC factors.

Serum from a grand multiparous Inuit (Eskimo) woman, who is HL-A identical but stimulatory in MLC with cells of her husband, contains strong ABCIL reactivity. This serum is operationally monospecific against a cell membrane determinant on lymphocytes, but not platelets, of some unrelated persons. Cells of those who are ABCIL positive with this serum always give a lower MLC stimulation index compared with their MLC responsiveness to cells that are ABCIL negative. This serum also contains good MLC inhibitory activity but only in those one way MLC reactions in which it reacts, by ABCIL, with the stimulating cells. It is postulated that the ABCIL activity is directed against a common MLC factor on lymphocytes.

Antigen-Antibody Reactions↗
PubMed1975

Antibody-dependent lymphocyte killer function in human immunodeficiency diseases.

Antibody-dependent cell immunity to the lymphocyte system (ABCIL) has been shown to be a function of a non-thymus-processed cell in the experimental animal. To evaluate its role in the human and to assess its clinical usefulness, we assessed ABCIL in twenty-five patients with various immunodeficiency (ID) syndromes. Our technique measures the lysis of 51Cr-labelled normal human lymphocytes coated with HL-A-specific antibody. Cytotoxicity is expressed as a percentage of 51Cr released after subtracting the spontaneous target cell release. Mean values in normals are 20+/-2 (s.e.). The ten patients with AB deficiency had a mean ABCIL of 7-9+/-2 (Pless than0-01). All eight patients with cellular ID had normal ABCIL (18+/-2), while the ten patients with combined ID had variable results. Effector cell function in the ABCIL test correlated (r=0-74; Pless than0-05) with the percentage of B cells in the peripheral blood. No correlation was found between ABCIL function and serum immunoglobulin levels or rosette-forming cells in the peripheral blood. There is a function for B lymphocytes other than as a precursor of antibody-synthesizing cells.

Adolescent↗
PubMed1974

Serological detection of mixed lymphocyte culture identity between cells that differ by one HL-A haplotype.

Antibody mediated cell dependent immune lympholysis (ABCIL), an extremely sensitive serological technique for detecting tissue sensitization, was used in a family segregation study. Two serums capable of demonstrating ABCIL were used to identify members of the family who differed by one HL-A haplotype but whose cells did not stimulate in mixed lymphocyte culture. Absorption study of one serum indicated that the ABCIL reaction of that serum was directed against a factor, independent of HL-A, that might be responsible for lymphocyte stimulation in mixed lymphocyte culture. Thus the ABCIL technique may be used to detect lymphocyte-defined gene products.

Antigens↗