[HBs antigen screening with Groupamatic. Inhibition of passive hemagglutination and latex test]. / Dépistage de l'antigène HBs sur les équipements Groupamatic. Inhibition de l'hémagglutination passive et test au latex.

Some agglutination tests for HBs Ag and anti-HBs detection may be easily automated. Reverse hemagglutination, needing a lengthy incubation and several steps to carry out is unfit for Groupamatic, but hemagglutination inhibition and latex agglutination may be used. Hemagglutination inhibition using selected human red cells (ORh+) coated with cesium chloride purified HBs Ag, has been now routinely used at the C.N.T.S. with visual reading for almost 2 years. Negative and positive controls are necessary. The anti-HBs serum utilized has to be checked daily to get sensitive detection. Every new batch of coated red cells (valid 4 to 6 weeks) is checked in microtiter plates in the laboratory, before being used on Groupamatic. Both positive and dubious results are systematically retested in RIA. We found only 0,5% of false positive. The sensibility of the test compared favourably with other third generation test as reverse hemagglutination. It was close to the results obtained with radio-immuno-assay or enzyme-immuno-assay and it was more sensitive than counter-immuno electrophoresis. 65,472 samples were tested in parallel: we were able to detect 97% of HBs Ag detected by RIA. False negative results were less than 1 per 10 000 and may be avoided by using citrated solution for the anti-HBs serum dilution (suppression of auto-agglutination of the red cells). Antigex TG (the most active batch of latex coated with guinea pig, anti-HBs antibody) made by Pfizer, gave good results on Groupamatic and automatic reading was possible. But more results are necessary using various batches, before to recommend such reagent.

Screening of HBs antigen and detection of corresponding antibodies on groupamatic equipment.

The widespread utilization of Groupamatic equipment for routine immunohaematological tests has increased the demand for serological procedures that can be performed with this machine. We describe the test method which was developed and with which the detection of HBs antigen has now been carried out routinely for 1 year. It is an automated haemagglutination inhibition reaction which is called GIPHA (Groupamatic inhibition of passive haemagglutination). The sensitivity corresponds to 2 CNTS units, the antigen weight for 1 unit being from 1 to 4 ng. The reproducibility is good; the percentage of false positive reactions is about 0.5% and that of technical problems 0.7%. The additional advantages of the machines are numerous, among which we have the possibility of 11 other simultaneous reactions. One of them is the detection of antibodies against HBs antigen, which is a passive haemagglutination test called PHAG (passive haemagglutination on Groupamatic).

[Detection and titration of anti-tetanus antibodies by passive hemagglutination]. / Dépistage et titrage des anticorps antitétaniques par hémagglutination passive.

Human red cells O Rh + are coated with purified tetanus toxoid, by means of chromic chloride as coupling agent. With this reagent and by passive haemagglutination technique, antitetanus antibodies can be automatically screened and titrated in blood donnors plasmas, on Groupamatic equipments. Comparative results of three techniques: counter immunoelectrophoresis; manual passive haemagglutination; automatic passive haemagglutination are given, 4, 92 percent among the 1.219 tested blood donnors plasmas have an antibody greater than or equal to 5 U.I., 16, 24 percent have a titre between 1 and 5 U.I.

[Detection of HBs antigen by hemagglutination inhibition tests; experiment with standardization]. / Détection de l'antigène HBs par inhibition de l'hémagglutination passive; essais en vue d'une standardisation

The standarization of a reagent for automated detection of HBs antigen by an inhibition of the hemagglutination reaction is described. Its advantages are its specificity, its fast efficiency, its low cost. But, its handling is delicate and requires a good technicity.