Table IV. RF pattenlS in 415 samples with elevation of one or more RF classes and their earrelation
with agglutination.
Elevated
Nomber
(%)
RF class(es) :
orsamples
lgMRF only
112 (27%)
lgG RF only
47 (11%)
IgARF only
39 ( 9%)
lgM+IgGRF
16 ( 4%)
lgM +lgARF
109 (26%)
lgG + IgARF
10 ( 2%)
lgM + lgG + IgA RF
82 (20%)
Total
415 (100%)
to be able to distuinguish at an early stage arthritic
patients who have an isolated elevation of I
gM
RF
from thosewith raised lgMRF
in
combinationwith
IgA RF. Conventional agglutination tests do not
discriminate between such patients. Furthermore,
most patients with elevation of only IgA RF, who
are Iikely have a poor prognosis, are negative when
tested only by agglutination techniques.
We therefore believe that that dass specific
measurement of RF is superior to agglutination
both for diagnostic and prognostic evaluation of
arthritic patients.
Many studies have dealt with the relationship
between disease activity and RF [6, 8, 19, 25, 26].
Elevated RF
Fig. I . Relation between elevatedRF andRA.
The bars show the percentage ofindividuals with
elevated RF that have RA (modified from
reference 23 with permission).
Klinisk kemi
i
Norden 4, 1994
<
c:
40
30
.c.
-
o
Percent also positive
by agglutinatinon
80%
34%
41%
81%
94%
50%
100%
It
has, however, not been convincingly shown that
the levels of different RF classes are useful for
monitoring disease activity. Other laboratory para–
meters, such as erythrocyte sedimentation rate and
C-reactive protein, are probably better in this
respect.
We conclude that immunologkal laboratories
providing service for rheumatoid patients should
carefully consider the advantages ofusing tests that
can discriminate between different RF classes. We
believe that measurement of individual RF classes
can give the dinidan more valuable diagnostic and
prognosticinformation about patients with arthritis,
information that the conventional agglutination
tests are unable to give.
Rose-Waaler
test pos.
(n=80)
lgMRF
on
ly
(n=39)
32%
lgM RF
+
lgA RF
(:t
lgG RF)
(n=62)
127
