434
C.H.J. Lamers
arated the hapten— and carrier—reactive cells from goldfish, using nylon
wool
column
adherance.
The hapten—reactive cells appeared to be present in prome—
phros, but not in
the
thymus,
suggesting
that
hapten—reactive
cells
are
"B—like" cells.
It
is
possible to induce proliferation of carp lymphocytes
in_ vitro
by
mammalian
T—cell
(PHA,
Con
A)
and
B—cell
(LPS) mitogens (Liewes et al.,
1982a).
However, there are no indications for a differential
mitogenic
res—
ponsiveness
of
leucocytes
originating
from
different
lymphoid
organs.
Recently Caspi et al.
(1984), studied sequential and simultaneous stimulation
of
carp peripheral blood lymphocytes by PEA, Con A and LPS°
The results indi—
cated that
two
distinct cell populations were reactive to PEA/Con A
and
LPS.
Moreover,
these
two
cell populations, if cultured longterm with eithr PHA or
LPS, showed different cell morphology, which was comparable with
the
picture
of
mammalian
activated T— and B—cells, lymphoblasts and plasmablasts respec—
tively.
Lymphocyte surface markets.
All lymphocytes of carp
and
goldfish,
in—
cluding
thymocytes, are positive for slg, when analyzed with conventional an—
tisera
to
serum
lg (Emmrich et al., 1975;
Warr et
al., 1976).
The
supposition that teleost thymocytes bear slg seems to be supported by
the observation that most monoclonal antibodies
(MoAbs) made against carp thy—
mocytes recognize serum lg (Secombes et al., 1983a).
However, in the same ex—
periments
only
a
small
percentage of the MOAbs made against serum lg react
with thymocytes.
A possible explanation for these data
is
the
presence
of
only
part of the antigenic determinants of serum lg on the surface of teleost
thymocytes.
This is
in agreement with Ambrosius et al.
(1982), who
provided
evidence
that
the
(antigen—specific) receptor on carp thymocytes is based on a
dimer of
slightly modified serum lg heavy chains, homologous to the
mammalian
“
chain,
whereas
light chains are lacking.
Recently Folkerts et al.
(1985)
confirmed
that
the lg related determinant on T—like cells is an antigen recep—
tor.
MoAbs positive for both serum lg and thymocytes blocked T—cell activity
in a mixed lymphocyte culture (MLR), through an
irreversible
effect
on
the
responder cells, but not on the effector cells.
Based on the observation that some anti—serum lg MoAbs do not react
With
lymphocytes
from
the thymus, Secombes et al.
(1983a) have tried to identify
lymphocyte subpopulations.
Their results indicate that 40%
or
less
of
the
lymphocytes
from
spleen
and
pronephros
display
a
positive reaction with
anti—lg MoAbs and might thus be considered equivalent
to
B—lymphocytes
from
higher vertebrates, carrying lg as the antigen—specific receptor on their sur—
face.
Whatever the remaining lymphocytes carry on their surface cannot
be
a
complete
lg
molecule,
and
from
foregoing it might be suggested that these
cells might be considered as T—lymphocyte equivalents.
When carp
lymphocytes
are
depleted
of
those B—cell equivalents, e.g.
by "panning" procedures, the
mitogenic response of the remaining lymphocyte subpopulation to PHA was signi—
ficantly enhanced (Folkerts et al., 1985).
In conclusion, there is clear evidence for
functional
heterogeneitY
°f
CârP
lymphocytes, but the use of MoAbs has made possible to separate these po—
pulation5, which can
be
designated
as
functional
equivalents
of
Band
T—lymphocytes of higher vertebrates.
LYMPHOID ORGANS.
_
The lymphoid organs Of C8rP are:
thymus, spleen, head kidney
and
trunk
1975)Moreover, high numbers of lymphoid cells are present
es
ina
mucosa
D
'
.
'
organs
is visualized in
et
al
,
1980).
The
location Of
carp lymphold
ÏËÊ.ËËZËEÊ is a paired organ located near the branchial cavity and is CO“
C.H.J. Lamers
arated the hapten— and carrier—reactive cells from goldfish, using nylon
wool
column
adherance.
The hapten—reactive cells appeared to be present in prome—
phros, but not in
the
thymus,
suggesting
that
hapten—reactive
cells
are
"B—like" cells.
It
is
possible to induce proliferation of carp lymphocytes
in_ vitro
by
mammalian
T—cell
(PHA,
Con
A)
and
B—cell
(LPS) mitogens (Liewes et al.,
1982a).
However, there are no indications for a differential
mitogenic
res—
ponsiveness
of
leucocytes
originating
from
different
lymphoid
organs.
Recently Caspi et al.
(1984), studied sequential and simultaneous stimulation
of
carp peripheral blood lymphocytes by PEA, Con A and LPS°
The results indi—
cated that
two
distinct cell populations were reactive to PEA/Con A
and
LPS.
Moreover,
these
two
cell populations, if cultured longterm with eithr PHA or
LPS, showed different cell morphology, which was comparable with
the
picture
of
mammalian
activated T— and B—cells, lymphoblasts and plasmablasts respec—
tively.
Lymphocyte surface markets.
All lymphocytes of carp
and
goldfish,
in—
cluding
thymocytes, are positive for slg, when analyzed with conventional an—
tisera
to
serum
lg (Emmrich et al., 1975;
Warr et
al., 1976).
The
supposition that teleost thymocytes bear slg seems to be supported by
the observation that most monoclonal antibodies
(MoAbs) made against carp thy—
mocytes recognize serum lg (Secombes et al., 1983a).
However, in the same ex—
periments
only
a
small
percentage of the MOAbs made against serum lg react
with thymocytes.
A possible explanation for these data
is
the
presence
of
only
part of the antigenic determinants of serum lg on the surface of teleost
thymocytes.
This is
in agreement with Ambrosius et al.
(1982), who
provided
evidence
that
the
(antigen—specific) receptor on carp thymocytes is based on a
dimer of
slightly modified serum lg heavy chains, homologous to the
mammalian
“
chain,
whereas
light chains are lacking.
Recently Folkerts et al.
(1985)
confirmed
that
the lg related determinant on T—like cells is an antigen recep—
tor.
MoAbs positive for both serum lg and thymocytes blocked T—cell activity
in a mixed lymphocyte culture (MLR), through an
irreversible
effect
on
the
responder cells, but not on the effector cells.
Based on the observation that some anti—serum lg MoAbs do not react
With
lymphocytes
from
the thymus, Secombes et al.
(1983a) have tried to identify
lymphocyte subpopulations.
Their results indicate that 40%
or
less
of
the
lymphocytes
from
spleen
and
pronephros
display
a
positive reaction with
anti—lg MoAbs and might thus be considered equivalent
to
B—lymphocytes
from
higher vertebrates, carrying lg as the antigen—specific receptor on their sur—
face.
Whatever the remaining lymphocytes carry on their surface cannot
be
a
complete
lg
molecule,
and
from
foregoing it might be suggested that these
cells might be considered as T—lymphocyte equivalents.
When carp
lymphocytes
are
depleted
of
those B—cell equivalents, e.g.
by "panning" procedures, the
mitogenic response of the remaining lymphocyte subpopulation to PHA was signi—
ficantly enhanced (Folkerts et al., 1985).
In conclusion, there is clear evidence for
functional
heterogeneitY
°f
CârP
lymphocytes, but the use of MoAbs has made possible to separate these po—
pulation5, which can
be
designated
as
functional
equivalents
of
Band
T—lymphocytes of higher vertebrates.
LYMPHOID ORGANS.
_
The lymphoid organs Of C8rP are:
thymus, spleen, head kidney
and
trunk
1975)Moreover, high numbers of lymphoid cells are present
es
ina
mucosa
D
'
.
'
organs
is visualized in
et
al
,
1980).
The
location Of
carp lymphold
ÏËÊ.ËËZËEÊ is a paired organ located near the branchial cavity and is CO“