Læknablaðið : fylgirit - 01.05.1978, Qupperneq 128

<D <D
M +»
O -rt
« 4»
Fig.l: Relationship between the Wsialer-Rose titer, th.e RA-Latex titer
and the IF-test. + *> IF-test of IgM-Antiglohulin positive
- = IF-test of IgM-Antiglobulin negative.
serum IgG to some of its bindingplaces. This
was further supported by fractionation studies
with Sephadex G-200 chromatography of serum.
Two fractions were obtained, I) with positive
reaction in the IF-test for IgM- and IgG-RFwith
titers 1:40 and 1:20. By DTT treatment the
reactions became negative. A second fraction
II) with negative IgM-RF reaction and positive
IgG-RF reaction (titer 1:40) in the IF-test had
the IgG-RF titer unchanged after DTT treatm'ent
of the fraction.
The specificity:
To detect the specificity of the reaction of the
amboceptor, sera with a known pos. Waller-Rose
and RA-Latex reaction and pos. IF-test for IgM-
RF (untreated serum) and IgG-RF (DTT treated
serum) were used in a series of experiments
with varying amboceptor. The amboceptors are:
coat I : rabbit IgG, split by pepsin in acetate
buffer at pH = 4.0 in 24 hours at 37°C.
coat H : rabbit IgG incubated 24 hours with
acetate buffer without pepsin at pH =
4.0, 37°C.
coat HI: untreated rabbit IgG.
The reactions for IgM-RF before DTT treatment
and IgG-RF after DTT treatment were all nega-
tive when using coat I in the test system, but
positive when coat II and HI were used as seen
in table H.
That the pepsin treatment of the amboceptor
lead to destruction of the Fc-fragment of the
rabbit-IgG could be shown by S-zoneuItracentri-
fugation, which for coat I gave a sedimentation-
coefficient S = 4.7 according to the F (ab)2 part(ll).
126