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Biomedical subjects

M E Medof

Publications and source records attributed to M E Medof.

124 records · Page 7Linked to original sources
PubMed1982

Effect of incomplete double strandedness of test DNA on DNA binding results.

Four commercial radiolabeled "double-stranded" DNA preparations were chromatographed on BNDC to determine proportion of incompletely ds-DNA in each. Sera from 10 patients with rheumatic diseases other than SLE, chosen for strong binding to one of the commercial DNAs, were retested with each of the other DNAs. Binding to each commercial DNA by all 10 sera was proportional to percent of that DNA containing ss-regions and in nine cases declined to zero for completely ds-DNA.

Adult↗
PubMed1982

Competition for immune complexes by red cells in human blood.

Antigen:antibody complexes, prepared with 125I-bovine serum albumin and guinea or rabbit antibody, were added to serum and blood cells from normal individuals and binding studied. When antigen:antibody were pre-incubated with serum in varying proportions for 30 min at 37 degrees C and then mixed with washed unseparated cells, binding increased to a maximum (70% of added complexes) and then decreased as serum to antigen:antibody proportions were increased. Separation of cells revealed that following maximal binding to unfractionated cells, complexes were predominantly associated with red blood cells (RBC), even though complexes bound less per cell to RBC than to white blood cells following addition of complexes to separated cells. Binding to RBC was reduced by zymosan treatment of serum and abolished by heat inactivation or substitution of non-primate RBC (known not to possess C3b receptors) for human RBC, indicating that binding to human RBC was via C3b receptors. When antigen:antibody were incubated at 37 degrees C directly with serum and unfractionated blood cells, maximal binding occurred after 2-4 minutes and declined thereafter. Identical kinetics were observed when purified RBC were substituted for whole blood cells. When diluted or hypocomplementemic (systemic lupus erythematosus) serum was substituted for neat serum, maximal binding was delayed and sustained. Our findings suggest that RBC in human blood can compete with other cell types for immune complexes at that stage during the sequence of reactions between complexes and complement when complexes are able to bind to C3b receptors.

Animals↗
PubMed1982

Restoration of normal interactions between immune complexes and systemic lupus erythematosus blood cells by normal serum.

Blood cells from patients with systemic lupus erythematosus (SLE) and from healthy control subjects were studied for their ability to bind exogenous immune complexes. Cells were mixed with experimental complexes (prepared from 125I-radiolabeled bovine serum albumin [BSA] and guinea pig antiserum to BSA) after incubation of the complexes with autologous serum in variable proportions. Unfractionated blood cells from SLE patients bound fewer added complexes (mean +/- SD = 39.8% +/- 12.9%) than cells from normal controls (mean +/- SD = 63.6% +/- 9.5%) (p less than 0.001); as much as 128-fold (mean = 23-fold) higher (p less than 0.01) proportions of serum to complex were required to optimize the lower binding. When SLE blood cells were mixed with complexes preincubated with normal sera instead of autologous SLE sera, SLE cells bound increased amounts of added complexes, and binding was optimal at the same lower proportions of serum to complex as for normal cells. When normal cells were mixed with complexes preincubated with compatible SLE sera in place of endogenous normal sera, binding to normal cells decreased to SLE levels, and the same higher proportions of serum to complex were required to optimize the lower binding as for the SLE cells. Similar results were obtained when binding to purified mononuclear cell preparations from SLE patients and controls was studied. When comparative studies were performed at high complex-to-cell ratios with complexes prepared using normal sera, SLE cells bound fewer complexes per cell than normal cells. These results indicate that although abnormalities in SLE cells are demonstrable, the major factor accounting for aberrant interaction between immune complexes and SLE cells resides in alterations in SLE sera.

Adolescent↗
PubMed1982

Kinetics of interaction of immune complexes with complement receptors on human blood cells: modification of complexes during interaction with red cells.

Antigen-antibody complexes, composed of 125I-BSA and guinea-pig or rabbit antibody, were incubated at 37 degrees C with human blood cells suspended in autologous serum and kinetics of binding analysed. When purified polymorphonuclear (PMN) or mononuclear cells (MNC) were studied, maximum binding was observed within 8 min, and immune complexes (IC) remained associated with cells even after 1 hr. When cells were studied unseparated (in the same amount of serum), maximum binding was observed slightly earlier (within 4 min), but within 15 min most of the IC were found in the serum. Separation of cell types at the time of maximal binding and studies with cell preparations depleted of different elements revealed that binding was principally to red blood cells (RBC). IC recovered in the serum 16 min after addition to unseparated cells bound very slowly to purified PMN or MNC; binding after 30 min was 10-15% of that observed with fresh IC at 8 min. Ultracentrifugal analysis revealed that reduction in binding efficiency correlated with decrease in the size of IC. RBC isolated after binding and release of IC bound newly-formed IC was identical rapidity and capacity as fresh RBC, indicating that receptors were not altered by IC. Kinetics studies with serum in the absence of cells suggested that interaction with RBC accelerated the rate of change in binding properties of IC. Rates of binding and release were independent of antigen/antibody ratio but were slowed and binding to RBC sustained when diluted or hypocomplementaemic (SLE) serum was substituted for neat serum. Our results suggest that competition for IC by RBC is associated with loss of ability of IC to bind to other blood cell types and reduction in size of IC, and that abnormalities of complement can lead to prolonged association of IC with RBC.

Antigen-Antibody Complex↗
PubMed1982

Stimulation of NK-like CMC by skin test antigens in vitro is depressed in patients with SLE.

Peripheral blood mononuclear cells isolated from patients with systemic lupus erythematosus (SLE) developed lower levels of skin test antigen stimulated natural killer cell like cell-mediated cytolysis (NK-like CMC) than did similar cells from age and sex matched non-SLE volunteers. When the subjects were grouped according to disease activity the cells from the patients with mild disease activity developed lower levels of NK-like CMC than did those from the non-SLE control subjects. The cells isolated from SLE patients who had moderate to severely active disease developed little if any NK-like CMC after exposure to various skin test antigens. Greatly decreased skin test antigen stimulation of NK-like CMC in the cells from the SLE patients with more active disease did not appear to be due to therapy with corticosteroids or to a suppressor effect on this response by monocytes present in the peripheral blood mononuclear cell populations.

Adult↗
PubMed1981

Circulating immune complexes in neurologic disease.

Sera from patients with multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), subacute sclerosing panencephalitis (SSPE), and myasthenia gravis (MG) were assayed for immune complexes. Three techniques were used: a modified Raji cell assay, the 125I-Clq polyethyleneglycol assay, and a solid-phase clq assay. Immune complex levels were elevated in sera of some patients with MS, ALS, and SSPE, but the elevations were modest when compared with active systemic lupus erythematosus (SLE). In some cases, abnormalities were detected in only one assay system; in other cases, abnormalities were detected by two or three assay systems. In MS, immune complex elevations correlated with active disease and with decreased suppressor cell activity. Of two ALS patients with antecedent poliomyelitis, one had markedly increased levels of immune complexes in two assays. In MG, levels of immune complexes did not differ from those of controls.

Adolescent↗
PubMed1981

Generation of suppressor cells by aggregated human globulin.

We have studied the capacity of aggregated human globulin, a model for immune complexes, to induce suppressor cells which modulate a predominantly T cell response, i.e. the proliferative response of autologous mononuclear cells to concanavalin A. We utilized a soluble aggregated human globulin preparation depleted of both high molecular weight (greater than 4 x 10(6) daltons) insoluble aggregates and monomeric IgG. The mean per cent suppression induced by mononuclear cells preincubated with aggregated human globulin for 96 hr was 39 +/- 8%; monomeric IgG did not induce significant suppression (4 +/- 6%). We found a close correlation between the magnitude of suppression induced by preincubation for 96 hr with aggregated human globulin and that induced by preincubation with concanavalin A. Kinetic analysis indicated that suppressor cell induction by aggregated human globulin required 48 hr of preincubation; suppressor cell induction by concanavalin A required 24 hr. Aggregated human globulin-induced suppression was not associated with DNA synthesis as measured by 3H-thymidine uptake. The findings suggest that immune complexes can modulate immunoregulation.

Adult↗
PubMed1981

Ability of complement to release systemic lupus erythematosus immune complexes from cell receptors.

Endogenous immune complexes present in sera from 10 different patients with systemic lupus erythematosus (SLE) in an active phase were allowed to bind to Raji cells; the ability of intact complement to release the cell-bound complexes from receptors was then examined. Fresh normal human serum, or, alternatively, zymosan-pretreated serum, was added to the complex-bearing Raji cells. Immune complexes remaining bound to Raji cell receptors after increasing times at 37 degrees C were quantitated by addition of 125I-labelled antiglobulin, after removal of serum by washing. In all 10 cases, complement-dependent release was observed. In parallel control studies performed under identical conditions, immune complexes prepared in vitro from bovine serum albumin (BSA) and guinea-pig anti-BSA antibody were used in place of the endogenous SLE complexes. The experimental complexes were released by fresh serum, but not by zymosan-treated serum, but not by zymosan-treated serum, when studied using either 125I-labelled anti-guinea-pig Ig or 125I-labelled complexes alone. The results suggest that intact complement can alter the immune complexes present in SLE sera and influence their interaction with receptors on lymphoid cells. The results further raise the possibility that hypocomplementaemia secondarily due to consumption of complement by immune complexes may contribute to the persistence of the complexes.

Adult↗
PubMed1980

Histocompatibility antigens and gold toxicity: a preliminary report.

To investigate the possibility that genetic factors are involved in the outcome of gold salt therapy for arthritis, histocompatibility antigens (HLA) were determined for 32 patients treated with gold salts. A comparison of patients who achieved remission following gold therapy with those who did not failed to demonstrate any difference in HLA antigens. Patients who had experienced adverse reactions during gold therapy were found to have an increased frequency of the HLA-B12 antigen. Gold toxicity occurred in 69.2 per cent (9/13) of patients with the B12 antigen, compared with 26.3 per cent (5/19) of patients without the antigen (P = 0.035).

Adult↗
PubMed1979

Suppressor cell function in multiple sclerosis: correlation with clinical disease activity.

Concanavalin A (Con A)-activated suppressor cell activity was determined in multiple sclerosis (MS) patients who had been assigned to one of three subgroups, those with active disease, those recovering from a flare-up, and those with stable disease. The level of suppression induced by the Con A-activated suppressor cells on the mitogenic response of autologous peripheral blood lymphocytes was reduced in patients with active disease (3 +/- 8%) compared with stable patients (30 +/- 8%), patients recovering from a flare-up (62 +/- 5%), and controls (40 +/- 5%). As a measure of the actual amounts of suppressor factors released, the effect of supernatants from the Con A-activated cells on the proliferative activity of a dividing cell line (L cells) was determined concurrently. The inhibitory effect of supernatants from activated cells was reduced in active and stable MS patients (7 +/- 3%) compared to controls (21 +/- 4%). Three of 4 with active MS showed mildly elevated immune complex levels as measured by the Raji cell technique; each of these patients had low suppressor activity. Levamisole (1 microgram per milliliter) failed to alter suppressor cell activity in our in vitro system.

Concanavalin A↗
PubMed1977

Characterization of DNA used to assay sera for anti-DNA antibodies; determination of the specificities of anti-DNA antibodies in SLE and non-SLE rheumatic disease states.

Commercial 14C-labeled KB cell DNA, widely used to assay sera for anti-DNA antibodies, was chromatographed on benzoylated-naphthoylated-DEAE-cellulose (BNDC) and on hydroxyapatite (HAP). On BNDC, only 25% of the 14C label eluted with 1 M NaC1 (KB fraction I) characteristic of ds-DNA. Fifty-five percent of the label eluted with 50% formamide-1 M NaC1 (KB fraction II) characteristic of ss or denatured DNA. On HAP, however, none of the 14C label eluted with 0.2 M phosphate buffer as anticipated for ss-DNA, but, rather, all of the 14C label eluted with 0.4 M phosphate, characteristic of ds-DNA. after pretreatment with S1 endonuclease of Aspergillus oryzae, which selectively digests ss regions, however, 42% of the 14C label was lost from the 0.4 M phosphate peak. These results indicated that more than half of this 14C-KB-cell DNA preparation was ds-DNA with ss regions which was undetectable by HAP chromatography. 3H-ds-DNA and circular 3H-ss-DNA prepared from T7 and phiX174 bacteriophage, respectively, were found to be chromatographically pure on both BNDC and HAP. None of 10 non-SLE sera (rheumatoid arthritis 3, mixed connective tissue disease 4, scleroderma 1, ulcerative colitis 1, and pulmonary fibrosis with chronic active hepatitis 1), previously believed to contain anti-ds-DNA antibodies on the basis of KB cell DNA testing and detectable antibodies against KB fraction 1 or T7 DNA: all of 10 KB cell DNA positive SLE sera had antibodies against both. Additionally, none of the 10 non-SLE sera had antibodies against KB cell DNA when retested with DNA that had been pretreated with S1 endonuclease. Seven of these 10, however, as well as all 10 SLE sera, had antibodies against phiX174 DNA, KB fraction II DNA and alkali-denatured T7 DNA. The data support the conclusions that 1) false positive tests for anti-ds-DNA antibodies can result from contamination of ds-DNA with ds-DNA having ss regions, and 2) non-SLE sera do not contain antibodies specific for ds-DNA at levels comparable to those found in SLE sera but rather contain high levels of antibodies reacting with ss regions or mixed DNA.

Antibodies↗
PubMedDate not supplied

Raynaud's phenomenon and initially seronegative mixed connective tissue disease.

We report 2 young women with Raynaud's phenomenon who later developed the laboratory and clinical features of mixed connective tissue disease (MCTD). Antibodies to extractable nuclear antigens were initially negative and remained so far several years before becoming positive. Raynaud's phenomenon is common in MCTD, but laboratory and clinical evidence of the latter may not be present initially.

Adolescent↗