The detection of antibodies to Mycobacterium tuberculosis by microplate enzyme-linked immunosorbent assay (ELISA)

The detection of antibodies to Mycobacterium tuberculosis by enzyme-linked immunosorbent assay has proved to be a potentially useful technique for the serodiagnosis of tuberculosis. The technique is capable of full automation. The use of a purified antigen should further improve the sensitivity of the method.

Gastric lesion in dermatitis herpetiformis

Five of 33 patients with dermatitis herpetiformis (DH) were found to have gastric parietal cell antibody in their sera, whereas it was not found in 30 healthy controls of comparable age distribution. Fifteen of the patients with DH underwent further studies to investigate the histological and functional state of their gastric mucosa. Atrophic gastritis was found in all five patients whose sera contained gastric parietal cell antibody and in three of 11 patients with no antibody in their sera. In addition, there was marked impairment of acid secretion in the DH group as a whole, but, apart from one patient with overt pernicious anaemia (PA), there was no evidence of malabsorption of B12.

The value of tests for antibodies to DNA in monitoring the clinical course of SLE. A long-term study using the Farr test and the DNA counterimmunoelectrophoretic method

Serial serum samples from fifteen patients with SLE, taken over periods varying from 6 months to 6 years, were tested for DNA binding capacity, DNA electroprecipitins (DNA-EP) and C'3 level to assess the value of these investigations in reflecting clinical disease activity. Patients with renal involvement showed a good correlation between high levels of DNA binding, low serum C'3 and disease activity and typically, their DNA-EP was negative. By contrast, patients without renal involvement in whom vasculitis was prominent, showed a poor correlation of DNA binding capacity to changes in the state of their disease although the DNA-EP test was persistently positive. It was also apparent that both the DNA-BC and C'3 can show marked variation in response to alterations in treatment without accompanying clinical change. Although these serological tests, particularly the DNA binding capacity are of recognized value in the diagnosis of SLE, they serve most usefully as guides to long-term management when they can be related to the clinical pattern of the disease.

Eosinophil-specific and other granulocyte-specific antinuclear antibodies in juvenile chronic polyarthritis and adult rheumatoid arthritis

Sera from 151 children of whom 112 had juvenile chronic polyarthritis (JCP), and from adults with rheumatoid arthritis (RA), and from healthy pregnant females were tested for the presence of granulocyte-specific antinuclear antibodies (GS-ANA). These were detected in 20% of sera from cases of JCP, in 68% of adult RA, but in none of the controls. Eosinophil-specific ANA were the only ANA present in 18% of positive children and 54% of the positive adults. GS-ANA in children were predominantly IgG and of low titre. Heat-stable GS-ANA were detected in sera from eight children but none bound complement. The presence of GS-ANA was not significantly associated with sex, age of onset, duration of disease, mean active joint count, mean ESR, nor with the presence of fever, rash, splenomegaly, amyloidosis, pericarditis, or rheumatoid factor.

Enhanced uptake by guinea-pig macrophages of radio-iodinated human aggregated immunoglobulin G in the presence of sera from rheumatoid patients with cutaneous vasculitis

A competitive radiobioassay method for soluble immune complexes in sera has been used to study sera from patients with rheumatoid arthritis. Twenty-eight out of sixty-two sera from selected seropositive rheumatoid patients were found to produce enhanced uptake of radio-iodinated human aggregated IgG by guinea-pig macrophages in contrast with the inhibition of uptake seen with SLE sera. Twenty-two out of the twenty-eight enhancing sera belonged to patients with cutaneous vasculitis. None of the twenty-two sera from seronegative rheumatoid patients possessed enhancing properties and none of these patients had clinical evidence of vasculitis. Three patients with seropositive SLE had sera with enhancing properties and had cutaneous vasculitis. We have shown that the enhancement is probably due to the presence in sera of immune complexes or altered IgG bound to rheumatoid factor. The possible mechanism has been investigated and it appears that there is increased binding of radio-iodinated aggregated IgG to free valencies on rheumatoid factor already bound to immune complexes.

Detection of antibodies to mycobacterium tuberculosis by solid phase radioimmunoassay

The sandwich solid phase radioimmunoassay procedure has been adapted to the serological diagnosis of tuberculosis by the use of disposable plastic haemagglutination trays in which the wells were sensitized with soluble mycobacterial antigen and the subsequent uptake of globulin from test sera detected with radioiodinated antiglobulin. The influence of time and temperature of the incubation stages, pH, washing times, drying and the efficiency of various non-specific blocking agents have been studied. In an initial survey carried out on 319 sera the results obtained showed a good correlation with the presence or absence of established tuberculous infection.

Antireticulin antibodies in dermatitis herpetiformis and adult coeliac disease. Their relationship to a gluten free diet and jejunal histology

Antireticulin antibody was present in 17% of sera from thirty-five patients with dermatitis herpetiformis, 45% from twenty-eight patients with adult coeliac disease and none of thirty healthy controls. There was a higher incidence of antireticulin antibody(a) in patients on normal diets than in those on gluten free diets, and (b) in patients with subtotal villous atrophy than in those with partial villous atrophy. Two patterns of tissue staining were demonstrated, one of which was almost invariably associated with jejunal subtotal villous atrophy. The Ig class of the antibody was IgG in all instances but in 64% antibody of the IgA class was also present.

Antigenic properties of a non-collagenous reticulin component of normal connective tissue

Rabbit antisera raised against a saline-insoluble non-collagenous reticulin component (NCRC) of pig and human kidney gave immunofluorescent staining of basement membranes, stroma of liver and kidney and newly formed blood vessels in pig, rat and human tissue. The staining patterns closely resembled those reported for anti-reticulin antibodies, and both species-specific and species-shared determinants could be distinguished. Although the antisera reacted least with rat glomeruli in cryostat sections, rabbit immunoglobulin localized persistently but harmlessly in the renal glomeruli of rats given the antisera intravenously. Absorption with NCRC of sera from patients with gluten-sensitive enteropathy in most cases removed the anti-reticulin antibody characteristic of this group of diseases.

The comet pattern of nuclear immunofluorescence

The significance of the comet pattern of nuclear staining seen when immunofluorescent tests for antinuclear antibodies (ANA) are carried out on unfixed sections of liver has been studied. Fifty-two of fifty-five ANA positive sera tested gave the pattern; there was no correlation with clinical diagnosis nor with the presence of antibodies to DNA.

The demonstration of comet staining was dilution-dependent with many of the sera and experimental evidence suggests that nuclear material in antigen–antibody complexes resulting from reaction with potent ANA is prevented from diffusing, whereas with less potent ANA diffusion occurs.

Use of peroxidase-conjugated antiglobulin as an alternative to immunofluorescence for the detection of antinuclear factor in serum

A method of detecting serum antinuclear factor by the use of antiglobulin conjugated with horseradish peroxidase has been compared with a standard procedure using a fluorescent label. The horseradish peroxidase conjugate was evaluated by block titration against positive serum and by its performance as a test reagent for screening and titrating sera. It is concluded that the horse-radish peroxidase method, in which an ordinary light microscope is employed, provides a satisfactory alternative to immunofluorescence for routine tests for antinuclear factor.