Critical aspects of the 125I-C1q binding assay for detecting immune complexes in tumor patients.

Clinical studies on C1q binding activity in tumor patients showed contradictory results and it was suggested that methodical problems might be partly responsible for those discrepancies. Therefore, precision of the C1q binding assay when testing tumor sera, influences of assay modifications on test results and possible interfering substances were investigated. Compared to aggregated human IgG and BSA: anti-BSA complexes as standards the C1q binding material in tumor sera was more unstable after freezing-thawing and distinctly more susceptible to methodical influences like testing with different 125I-C1q preparations or variations of PEG concentration and ionic strength of PEG solution. Addition of heparin and fibrinogen influenced the C1q binding of some tumor sera more than the C1q binding of standards and normal sera. Thus, instability and sensitivity to methodical influences of the C1q binding material have to be considered, when clinical studies using the C1q binding assay to detect immune complexes in tumor sera are interpreted.

Establishment of a bovine leukosis virus-free dairy herd.

A large dairy herd was established free of bovine leukosis virus (BLV) infection at the US Dairy Forage Research Center, Madison, Wis. Cattle introduced into the herd originated from BLV-infected herds, but only those negative for BLV antibodies by an agar gel immunodiffusion test were accepted there. Cattle that were found to be seropositive after their arrival at the new facility were promptly removed. Embryo transfer and artificial insemination were used to introduce new genetic stock into the herd. All recipients receiving embryos from BLV-positive donors and the 30 calves born from the successful transfers were seronegative at 21 months for BLV antibodies. Thus, under these conditions, embryo transfer and artificial insemination did not spread BLV. The agar gel immunodiffusion test was effective in screening cattle for BLV antibodies.

Chromatofocusing combined with the ELISA technique. A sensitive method for the analysis of immune complexes.

A sensitive method which permits analysis of IgG containing circulating immune complexes without detailed knowledge of the nature of the antigens and the specificity of the antibodies involved is described. Soluble BSA: anti-BSA were used as model immune complexes and isolated from serum. The procedure involves the use of gel chromatography for the separation of the high molecular weight fraction containing the immune complexes as measured by binding to 125I-labeled Clq, followed by absorption of the immune complex fraction to immobilized protein A-Sepharose CL-4B. After desorption from protein A-Sepharose the complexes were dissociated and separated into free antigen and antibody by chromatofocusing in the presence of urea. The isolated free antigen and antibody retained their immunological activity as shown by immunodiffusion, binding after their recombination to 125I-labeled Clq, and by recombining antigen and antibody with much enhanced sensitivity using a microplate ELISA system. By means of the ELISA recombination technique it is possible to analyze less than 1 microgram of BSA:anti-BSA model complexes. Application of this technique may provide more information about the nature of immune complex like material associated with diseases.

[Clinical significance of circulating immune complexes in patients with metastatic breast cancer]. / Klinische Wertigkeit der Bestimmung zirkulierender Immunkomplexe bei Patientinnen mit metastasierendem Mammakarzinom.

In 68 patients with metastatic breast cancer a follow-up study was performed to correlate circulating immune complexes (CIC) as detected by the C1q binding assay and the Raji cell radio immunoassay with the state of disease. Clinical examinations and determinations of CIC were carried out all four to eight weeks over at least six months. 19 patients were positive for CIC in the C1q binding assay and 12 in the Raji cell radioimmunoassay. There was no correlation between the results of both tests. In comparison 26 patients out of 68 with rheumatoid arthritis were positive in the C1q binding assay and 32 in the Raji cell assay. In these patients the results of both tests correlated significantly. There was only in a few cases of metastatic breast cancer a positive correlation between levels of CIC and changes of tumor burden. Furthermore, CIC did not prove to be of prognostic value.

Results of an epidemiological survey of enzootic bovine leukosis in the northern part of Lower Saxony and a preliminary communication of an examination into relationship between BLV-antibody development and calving.

The Agar-Gel-Immunodiffusion-Test as proposed by EEC has been carried out during the last 2 1/2 years within a defined test area of Lower Saxony. About 500 leukosis-infected herds with a total of about 20.000 head of cattle have been tested five times now within three to six months sequences. The AGIDT has proved to be an easy and very practical test for routine diagnosis in large scale surveys. Our results described again show the superiority of the glykoprotein-antigen over the ether-treated p24-antigen in the AGIDT. Slaughter of AGIDT-reactors within this population led to a fast decrease of leukosis-infection as detected by the test. Epidemiological herd-data show, that spreading of infection within a herd depends largely on direct contact between infected and noninfected animals. Moreover our data give rise to the suspicion that the manipulations during blood-sampling seem to be implicated in the spread of the disease within a herd. Possible reasons for inconsistencies of antibody-titer in infected animals are discussed.