A platelet indirect radioactive Coombs test (PIRC) has been described. The technique for purification and labelling the antiglobulin has been precised. This test allowed the typing of platelets in the PLA system by using an absorbed serum from a mother of a thrombocytopenic child. Six other families of neonatal thrombocytopenias were tested. In three of them, the mothers were found PLA(1) negative (PLA(2) PLA(2)). Among a panel of 93 platelets, two (0.022) were found PLA(1), negative. This PIRC test has many advantages compared to other tests such as platelet complement fixation, assay for blocking antibodies or antiglobulin consumption: it gives objective and quantitative results and is highly reproducible; anticomplementary serum may be tested.
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).
From January 1980 to December 1983, 989,907 blood donations were screened for HBsAg. A total of 1,345 was found HBsAg positive; 33 of whom were negative for anti-HBc (2.45%); in 10 cases HBeAg was present at a low level along with HBsAg. 2 of the 33 subjects were lost to follow-up. Late serum samples were available for 28 blood donors, and clinical and biological data only were known for the 3 others. An evolution of HBV markers was observed in each case; anti-HBc antibody became positive in 24 subjects (the 4 remaining subjects had a very short follow-up) ; HBeAg was positive at a high titer in 18 subjects and seroconversion to anti-HBe was observed in 7 individuals; HBsAg concentration increased in 21 subjects from 2 to 4,000 times and decreased in the 7 others. Seroconversion to anti-HBs was observed in 8 individuals. According to these serological, biological and clinical findings, different outcomes were observed: in 6 subjects too short a follow-up was available to allow appropriate classification, but there was evidence to suggest all probably developed clinical hepatitis; in 6 subjects asymptomatic hepatitis with rapid loss of HBsAg occurred; in 2 subjects asymptomatic hepatitis with the persistence of HBsAg at a low level and seroconversion to anti-HBe occurred; and in 17 subjects clinical hepatitis developed. These observations establish that most of the 33 blood donors were infectious at the time of their blood donation, and that anti-HBc antibody screening must not replace HBsAg screening for blood donations.
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