London's Pulse: Medical Officer of Health reports 1848-1972

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London County Council 1934

[Report of the Medical Officer of Health for London County Council]

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OBSERVATIONS ON THE GONOCOCCAL FIXATION TEST.
By W. Ralston, B.Sc., M.R.C.S., L.R.C.P., F.I.C., Assistant Pathologist, London
County Council (Whitechapel) Clinic.
After more than 17,000 sera had been tested, the control tubes in the gonococcal
fixation test failed to show the customary complete haemolysis in a certain batch of
sera which had been set up in the usual way. This was considered to indicate that
the titre of the guinea-pig serum had been incorrectly determined, and therefore too
little complement had been used. This batch of sera was retested the following day
with another supply of complement.
A critical discussion of the experience gained in the titration of the complement
in this particular guinea-pig serum may be useful to other pathologists who are
working with this test, or who are contemplating its introduction as a routine
practice. To avoid confusion the discussion has been arranged in sections as
follows:—
1. Technique for titration of complement in guinea-pig serum.
2. The construction of a table to convert unit volumes of dilutions of
guinea-pig serum into units or doses of complement.
3. The particular titrations described.
4. Critical examination of the results obtained in the titration of guinea-pig
serum.
5. Other possible sources of abnormal results.
1. Technique for titration of complement in guinea-pig serum.—A brief resume
is written to avoid frequent references to Prices's monograph1 on this test, and the
diagram illustrates the titration under discussion.
From the above diagram it will be seen that there are four rows of tubes in the
rack. Each tube first receives one volume of that dilution of complement (guineapig
serum) indicated at the foot of its column. This is followed by one volume of
.9 per cent. saline solution in the back and second rows of tubes, the front tubes
receiving two volumes. One volume of normal serum is next added to each tube of
the back and third rows only, and then the tubes of the third and second rows
receive one volume of diluted gonococcal antigen. Each tube should now contain
3 volumes of mixture and the rack is rapidly examined to check this, when any
inequality—perhaps due to a cracked or broken tube—will be detected. After
shaking well, one volume of 3 per cent. sensitised red cells is added to each front row
tube, and the rack is placed in a water-bath at 37.5° C. after another good shaking.
The progress of the laking in the front tubes is noted approximately every 5 minutes,
and the preliminary titre is read after 30 minutes. The other three rows of tubes
are incubated for a further 30 minutes and then one volume of sensitised red cells is
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