Læknablaðið : fylgirit - 01.06.1996, Blaðsíða 60

54
LÆKNABLAÐIÐ 1996; 82/FYLGIRIT 31
V-7. The potential regulatory role of
CD8+ T cells on CD4+ T cell
immune responses
Arnór Víkingsson*, ** , K Pederson***, D Mull-
Frá *Dpt of Immunology, Landspítalinn University
Hospital Reykjavík, ** Dpt of Medicine and ***Dpt
of Medical Microbiology & Immunology University
of Wisconsin, Madison, Wisconsin, USA
We have examined the potential role of CD8+ T
cells in regulating CD4+ T cell immune responses
during viral infection. The kinetics of CD4 versus
CD8+ T cell proliferation, IFNg production and
cytotoxic function was compared in virus infected
normal B6 and in Beta-2 microglobulin deficient
mice (B2M-), that are deficient in CD8 + T cells.
Flow cytometric analysis in normal B6 mice showed
biphasic T cell proliferative response, with early
CD8+ T cell proliferation and late CD4+ T cell
proliferation (day 5-7 versus day 9-12 postinfection,
respectively). IFNg production followed a similiar
pattern. Cytotoxic T cell (CTL) activity was only
detected within the CD8+ T cell subset. In B2M-
mice the lack of CD8+ T cells resulted in earlier
onset of CD4+ T cell proliferation and marked
CD4+ CTL activity. However, CD4+ T cell IFNg
production was relatively delayed in onset compar-
ed to the proliferative response.
These results suggest that CD8+ T cells suppress
CD4+ T cell proliferation and inhibit CD4+ CTL
function during viral infection.
V-8. IgA rheumatoid factor
subclasses in patients with
rheumatoid arthritis
Houssien DA, Þorbjörn Jónsson, Scott DL
Frá Dpt of Rheumatology, King's College Hospital,
London UK, Dpt of Immunology, Landspítalinn
University Hospital, Reykjavík
Several studies have indicated that elevation of
IgA rheumatoid factor (RF) is more specific for
rheumatoid arthritis (RA) than other RF isotypes.
Furthermore, high levels of IgA RF have in some
studies been associated with severe disease course
RA. Elevated levels of the IgAl and IgA2 RF sub-
classes have been demonstrated in patients with RA
but the clinical significance of this is still unclear.
Total IgA RF and the IgAl and IgA2 RF subclas-
ses were measured by ELISA in 144 patients with
RA. Radiological progression was assessed by the
Larsen score and disease activity was measured by a
EULAR core data set including erythrocyte sedi-
mentation rate (ESR), C-reactive protein (CRP),
the health assessment questionnaire (HAQ) and a
combined disease activity score (DAS).
Elevated serum levels of total IgA, IgAl and IgA2
RF were found in 50%, 60% and 50% of the RA
patients respectively. RA patients with elevated IgA
RF and both IgA RF subclasses had higher mean
Larsen score, DAS, ESR, CRP and HAQ than the
IgA RF negative patients. These differences were
highly significant.
The findings of this study confirm previous
reports showing that RA patients with elevated IgA
RF have a more aggressive and active disease than
IgA RF negative patients. Measurement of
individual IgA RF subclasses does not seem to give
more information about radiological progression or
clinical activity in patients with established RA than
measurement of tota! IgA RF.
V-9. Association between
radiological progression in
rheumatoid arthritis and rheumatoid
factor isotypes
Houssien DA, Þorbjörn Jónsson, Scott DL
Frá Dpt of Rheumatology, King’s College Hospital,
London UK, Dpt of Immunology, Landspltalinn
University Hospital, Reykjavík
High titer of rheumatoid factor (RF) has been
considered to be an indiciator of poor prognosis in
rheumatoid arthritis (RA). The relationship
between individual RF isotypes and disease severity
in RA has been analysed in several studies but find-
ings have been somewhat discordant. Thus, eleva-
tion of IgA RF has in some studies been associated
with the development of bone erosions, although
others have disagreed. Discordant findings can per-
haps be attributed to differences in methodology.
One hundred forty nine patients with established
RA according to the 1987 ACR criteria were inclu-
ded for the study (114 females/35 males, mean age
59.0 years and mean disease duration 10.9 years).
The modified Larsen score was used to evaluate
hand and wrist x-rays. IgM RF and IgA RF was
measured by ELISA using either horse or rabbit
IgG as antigen.
When rabbit IgG was the antigen patients with
elevated IgA RF or IgM RF had significantly higher
Larsen scores than the IgA RF and IgM RF negative
patients. Interestingly, patients with elevation of
only the IgM RF isotype did not have higher Larsen
scores than the RF negative patients. When horse
IgG was used as antigen only elevated IgA RF was
associated with high Larsen scores. No such signi-
ficant association was observed for IgM RF.
Elevation of IgA RF has closer association with
radiological progression in RA than elevation of
IgM RF. The type of antigen used to measure the
RF isotypes is important and may affect the rela-
tionship observed between radiological progression
and different RF isotypes.