Limitations of the Reiter Protein Complement-Fixation (RPCF) Test

Abstract

In previous papers we have recommended the application of the Reiter protein complementfixation (RPCF) test as a simple, reliable, and specific test for the sero-diagnosis of syphilis, provided that an adequate antigen and technique are used (De Bruijn and Bekker, 1957;Bekker, 1958Bekker, , 1959 (Bekker, 1960).No laboratory test for syphilis is perfect as regards specificity and sensitivity, and reactive results in non-syphilitic sera and non-reactive results in syphilitic sera do occur with all tests. For a correct interpretation of the results of the RPCF test its limitations must be recognized.In the present study some of the causes of unsatisfactory results of the RPCF test are discussed.Reactive RPCF Tests in Non-syphilitic Sera The specificity of the RPCF test is determined by the nature of the antigen. In our experiments the Reiter protein antigen was prepared according to De Bruijn (1957Bruijn ( , 1960 (De Bruijn, 1959), it was assumed * Received for publication March 13, 1962. that only the protein component is responsible for the reactivity with syphilitic serum. Searching after the origin of the "non-specific" positive results of the RPCF test, De Bruijn (1961) was able to demonstrate an antibody against the polysaccharide fraction of the Reiter treponeme in some of the sera. As this antibody was found in three out of 597 non-syphilitic and in twelve out of 205 syphilitic sera, its presence seems not to be a consequence of the treponemal infection. The possibility exists that this antibody is produced as a response to a micro-organism sharing the polysaccharide antigen with Reiter treponeme.We may conclude that in some cases a nonspecific reactive RPCF test can be explained by the occurrence in the serum of an antibody against the polysaccharide fraction of the Reiter treponeme, but that in the majority of the cases the cause is still obscure. Non-reactive RPCF Tests in Syphilitic SeraThe sensitivity of the RPCF test depends mainly on the technique by which it is performed. In our experiments Kolmer's technique was used with 1j exact units of complement (Portnoy and Magnuson, 1956), slightly modified in that the serum dilutions 1: 1, 1: 2, 1: 4, etc., were used. (The saline contained 100 mg. magnesium sulphate per litre). With this technique the sensitivity of the RPCF test at least equals that of the TPI test (Bekker, 1959), and in treated syphilitic patients its sensitivity is even greater (Bekker, 1960; Bekker and Onvlee, 1959). Exceptionally, a non-reactive RPCF test is found in syphilitic sera which react in the TPI test. In nearly all of these cases we could demonstrate that the negative result was due to a prezone (NeisserWechsberg) or related phenomenon.

Reactions of extracts of Reiter treponeme with syphilitic and non-syphilitic human sera in the single radial haemolysis technique

“…Its greater sensitivity may be due to the higher concentration of serum used. The large number of "false negatives" (i.e., positive sera not detected) obtained with the RPCFT is due to the prozone effect (Bekker, 1962); a prozone was seen with some sera in SRH but within the proper haemolytic zone. The occurrence of prozones in this type of test was reported by Strannegard, Grillner and Lindberg (1975) and Russell, McCahon and Beare (1975) but not explained.…”

Counterimmunoelectrophoresis of Reiter Treponeme Axial filaments as a diagnostic test for syphilis

“…Since that time, the Reiter protein complement fixation (RPCF) reaction has been used widely as a diagnostic test. False-positive reactions have been encountered in a small percentage of sera (4), and, as in all complement fixation tests, a few sera have given spontaneous nonspecific fixation (anti-complementary reactions). In an attempt to circumvent the latter difficulty, Banffer (1) applied the counterimmunoelectrophoresis (CIE) procedure of Bussard (5) to detect antibodies against the Reiter protein in the sera of syphilitic patients.…”

Η Σημασια Της Τρεπονημικης Δοκιμης Reiter (Rpcf) Εις Την Οροδιαγνωστικην Της Συφιλιδος

“…Ai μή είδικαί αύται αντιδράσεις της δοκιμής Reiter αποδίδονται είς τήν παρουσίαν είς τον όρον ώρισμένων ατόμων άντιπολυσακχαριδικοΰ αντι σώματος, συνδέοντος το συμπλήρωμα παρουσία του πολυσακχαριδικοϋ τμή ματος του αντιγόνου Reiter. Tò αντίσωμα τοϋτο παράγεται υπό ομολόγου αντιγόνου, άνευ ρίσκο μένου εις πολλά σαπροφυτικώς διαβιοΰντα τρεπονήματα, πιθανώς δέ και εις μικρόβια ή ιούς (Pillot et al 1965, Bekker 1962.…”

“…Ενίοτε παρά τήν ΐδανικώς έκτελουμένην τιτλοποίησιν, είναι δυνατόν ή ΣΣ επί άναραιώτων συφιλιδικων όρων να άποβή αρνητική. Τούτο οφείλεται εις φαινόμενον ζώνης ή προζώνης δι' ö καί συνιστάται όπως αί αντιδράσεις αδται εκτελούνται ποσοτικώς (Bekker 1962).…”