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Related post: also be isolated by separating cells on the Fluorescence Activated Cell
Sorter [FACS] according to the amounts of IgM, IgD, and total Ig they express
on their membranes. In general, B lymphocytes responsive to anti-p bear
relatively small amounts of IgM, intermediate to large amounts of IgD, and
large amounts of Ig, Thus, the anti-p responsive B lymphocyte has a high
ratio of IgD to IgM. It is interesting in this regard, that the B lymphocyte
defect caused by xid is associated with absence of proliferative responses to
anti-p and with the absence or diminished numbers of B lymphocytes which have
a high ratio of IgD to IgM.
Our current studies of this phenomenon are centered around three areas.
We have produced a series of monoclonal rat anti-p antibodies through fusion
of rat antibody producing cells with the BALB/c myeloma NS-1 . We Buy Meclizine are now in
the process of characterizing the specificity of these monoclonal antibodies
and determining whether they are capable of stimulating proliferative responses.
A second area of emphasis is that of producing cloned lines of B lymphocytes
reactive to anti-p (see Section C). Such cells should provide ideal materials
for the study of the cell biology of B lymphocyte activation by anti-p. It
is the study of early events in B cell activation which constitutes the third
major area in which study has recently Buy Meclizine Online begun.
B. B Lymphocyte Ontogeny, Heterogeneity and Activation
1. CBA/N Mice and the xid Gene
Our general approach to the study of the functional diversity of B
lymphocytes has been based on the use of genetic systems. We have placed
particular emphasis on the x-1 inked genetic defect of CBA/N mice which is
characterized by a profound but discrete defect in B lymphocyte function.
This defect involves the failure of CBA/N mice and mice with CBA/N x-chromo-
somes to respond to certain thymus-independent (TI) antigens. These include
hapten derivatives of Ficoll, type III pneumococcal polysaccharide, and levan
and dextran and their hapten conjugates. In Where To Buy Meclizine contrast, mice with the CBA/N de-
fect respond to another group of TI antigens, which includes the TNP deriva-
tives of Brucella abortus (TNP-BA), lipopolysaccharide (LPS) and Nocardia
water soluble mitogen (NWSM). On the basis of the distinctive responsiveness
of CBA/N mice to these two sets of TI antigens, we proposed that they should
be separately designated. TI antigens to which CBA/N respond are designated
TI-1 antigens while those to which CBA/N mice do not respond are TI-2 antigens.
In general, neonatal mice are unresponsive to TI-2 antigens but do respond to
TI-1 antigens and alloanti-6 antibodies block in vitro responses to TI-2 Purchase Meclizine but
not TI-1 antigens. Finally, TI-1 antigens tend to be powerful polyclonal B
lymphocyte activators whereas TI-2 antigens are, for the most part, inactive
in this regard.
We have recently mapped the gene responsible for the CBA/N defect. This
gene, termed x-1 inked immunodeficiency gene ( xid ) , is found on the x-chromo-
some equidistant from the Ta (Tabby) and hyp (hypophosphatemia) genes.
2. The Lyb5 and Lyb7 Differentiation Antigens
Our working hypothesis is that the genetic defect of mice homozygous or
hemizygous for the xid gene involves the deletion of a subpopulation of B
lymphocytes. These deleted cells may either be mature members of a single B
lymphocyte lineage or members of one of two distinct lineages of B lymphocytes,
With this in mind, we produced antisera which identify the subpopulation(s) of
B lymphocytes absent in mice with the xid determined defect. Although a
variety of immunization procedures were tried, the one which was successful
involved Purchase Meclizine Online immunization of C57BL/6 mice with DBA/2 spleen cells. This serum,
after absorption with DBA/2 thymocytes and spleen cells from defective (CBA/N
X DBA/2)F-, male mice, contains two types of antibodies, anti-Lyb5.1 and anti-
Lyb7.1, which recognize antigenic determinants expressed on (DBA/2xCBA/N)F-,
male B lymphocytes but not on cells from the defective (CBA/NxDBA/2)F, male.
The determinants recognized by these antibodies are each determined by an
independently segregating gene. The Lyb5 gene is not linked to the H-2 , Igh ,
Mis , or Lyb4 loci. The Lyb7 gene is also unlinked to the H-2 , Mis, and Lyb4
loci, but it is loosely linked to the Igh gene complex being located approxi-
mately 20 to 25 centimorgans from the IgGg locus.
The Lyb5 antigen is detected by the aoility of anti-Lyb5 antisera to lyse
B lymphocytes in the presence of complement. By contrast, anti-Lyb7 antisera
does not lyse B lymphocytes but it does inhibit the in vitro response of B
ymphocytes to TI-2 but not TI-1 Meclizine Buy antigens. This result is particularly pro-
vocative because it indicates that a membrane molecule encoded by a gene
linked to, but Meclizine Online separate from, the Igh gene complex has an important role in
regulating B lymphocyte activation.
We decided to search for monoclonal antibodies directed at markers of
mouse B lymphocyte subpopulations, both for the intrinsic value of any such
antibodies, and in the hope that we might find one which identified Lyb5 or
Lyb7. To do so, we immunized Lewis rats with DBA/2 spleen cells or
DBA/2 B lymphocytes, fused the rat cells to NS-1 and screened, using the
FACS, for monoclonal antibodies that bound B cells, or subsets of them.
Through this approach, we have obtained several Generic Meclizine anti-B cell antibodies,
most of which bind all B cells. In some instances, these antibodies
identify antigens expressed to different extents on B cell subsets, as
indicated by the finding that cells from mice with the xid determined
defect may express more or less antigen than control cells. Of these, three
are of special interest. They^are 17C9 which recognizes the ThB antigen;
14D10 which recognizes most Ig cells and another group of Ig~ cells which
may include B_cell Order Meclizine precursors, and 14G8, which appears to be Buy Cheap Meclizine principally
found on Lyb5 B cells. We are now in the process of a more precise deter-
mination of the cell types upon which these cells are expressed and in efforts
to purify and to functionally test these cells.
3. Responses of xid Mice to Polysaccharide Determinants
The study of the xid determined B lymphocyte defect of CBA/N mice
has been a major interest of Order Meclizine Online our laboratory for a considerable period of
time. We have recently extended our study of this genetic model in
several directions in an effort to gain greater insight into the nature
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