Anti-idiotypic antibodies specific for a pathologic anti-Pr2 cold agglutinin

The heterogeneity of human red cell (RBC) autoantibodies may be assessed by using anti-idiotypic antibodies. In this study, mouse monoclonal anti-idiotypic antibodies were produced against a pathologic RBC autoantibody with anti-Pr2 specificity. Epstein-Barr virus-transformed B-cell clones were established from a patient who had splenic lymphoma and associated immune hemolysis due to an anti-Pr2 cold autoantibody. Two of the eight clones producing this autoantibody were used to immunize mice for the establishment of hybridomas, and four monoclonal anti-idiotypic antibodies were isolated (2 IgG1 kappa and 2 IgM kappa). By the use of these anti-idiotypic antibodies, strong crossreactivity was seen on enzyme-linked immunosorbent assay with other anti-Pr2-producing clones from the same patient, but no cross-reactivity was seen with RBC autoantibodies from other individuals having anti-Pr or different specificities. Each of the anti-idiotypic antibodies inhibited hemagglutination (HA) by the patient's anti-Pr2 but failed to inhibit HA by antisera of a different RBC specificity. Cross-competition experiments indicated that all of the anti-idiotypic antibodies may recognize the same or a closely related idiotope on the anti-Pr2 autoantibody. These studies suggested that the four anti-idiotypic antibodies are directed against the same (or closely related) idiotypic determinant(s), unique to this patient's anti-Pr2 and located at or near the antigen-binding site. These anti-idiotypic antibodies may be useful tools for the study of this autoimmune response or for the development of immune therapeutic agents.(ABSTRACT TRUNCATED AT 250 WORDS)     

Surgical Division of an Accessory Atrioventricular Connection in the Posterior Septal Region Following Ventricular Fibrillation in the Wolff-Parkinson-White Syndrome*

Summary: Surgical division of an accessory atrioventricular connection in the posterior septal region following ventricular fibrillation in; the Wolff-Parkinson-White syndrome. N. Sadick,;D. K. Baird and J. B. Uther, Aust. N.Z. J. Med., 1978, 8 , pp. 652–655. A young man presented with atrial fibrillation and a rapid ventricular response which degenerated into ventricular fibrillation. Electrophysiological study demonstrated an accessory atrioventricular connection in the posterior septal region. This was sectioned to prevent recurrence of his arrhythmia. Post-operative electrophysiological study demonstrated that the surgical section was successful.     

Diagnosis of primary human herpesvirus 6 and 7 infections in febrile infants by polymerase chain reaction

Primary human herpesvirus 6 (HHV-6) and 7 (HHV-7) infections were identified in febrile children by qualitative and quantitative polymerase chain reaction (PCR) assays. Diagnosis was based on the differential detection of viral DNA in peripheral blood mononuclear cells (PBMC), but not in saliva. Six of 41 febrile infants, but none of seven non-febrile controls, were identified with primary infections (three HHV-6, three HHV-7). These children had significantly higher viral loads in PBMC (HHV-6, median 24213 genomes/10(6) PBMC; HHV-7, median 6,040,000 genomes/10(6) PBMC) than DNA-aemic, saliva PCR positive children (HHV-6, median 1606 genomes/10(6) PBMC, p < 0.01; HHV-7, median 7089 genomes/ 10(6) PBMC, p < 0.05). Viral DNA was detected in serum by PCR in only 50% of primary infections. All three children with primary HHV-7 infection had febrile convulsions. Thus PCR, including quantitative assays, may identify primary HHV-6 and HHV-7 infections when an appropriate combination of clinical specimens is used.     

A comparative laboratory diagnosis of malaria: microscopy versus rapid diagnostic test kits

Objective

To compare the two methods of rapid diagnostic tests (RDTs) and microscopy in the diagnosis of malaria.

Methods

RDTs and microscopy were carried out to diagnose malaria. Percentage malaria parasitaemia was calculated on thin films and all non-acute cases of plasmodiasis with less than 0.001% malaria parasitaemia were regarded as negative. Results were simply presented as percentage positive of the total number of patients under study. The results of RDTs were compared to those of microscopy while those of RDTs based on antigen were compared to those of RDTs based on antibody. Patients'' follow-up was made for all cases.

Results

All the 200 patients under present study tested positive to RDTs based on malaria antibodies (serum) method (100%). 128 out of 200 tested positive to RDTs based on malaria antigen (whole blood) method (64%), while 118 out of 200 patients under present study tested positive to visual microscopy of Lieshman and diluted Giemsa (59%). All patients that tested positive to microscopy also tested positive to RDTs based on antigen. All patients on the second day of follow-up were non-febrile and had antimalaria drugs.

Conclusions

We conclude based on the present study that the RDTs based on malaria antigen (whole blood) method is as specific as the traditional microscopy and even appears more sensitive than microscopy. The RDTs based on antibody (serum) method is unspecific thus it should not be encouraged. It is most likely that Africa being an endemic region, formation of certain levels of malaria antibody may not be uncommon. The present study also supports the opinion that a good number of febrile cases is not due to malaria. We support WHO''s report on cost effectiveness of RDTs but, recommend that only the antigen based method should possibly, be adopted in Africa and other malaria endemic regions of the world.