The ileal Peyer's patch (IPP) of lambs is a region of intense
lymphopoiesis and B cell development. Monoclonal antibodies against
ovine lymphocyte antigens have been used to characterise the IPP
lymphocyte. Three murine monoclonal antibodies against ovine IgM, IgGi
and Ig light chain were produced and are described fully. IgM and MHC
class II antigens are expressed on the vast majority of IPP cells
whilst cells bearing other serum Ig isotypes and T cell antigens are
rare. A novel Ig molecule appears to be coexpressed with IgM, it is
proposed that this is the ovine equivalent of IgD.The ileal Peyer's patch (IPP) of lambs is a region of intense
lymphopoiesis and B cell development. Monoclonal antibodies against
ovine lymphocyte antigens have been used to characterise the IPP
lymphocyte. Three murine monoclonal antibodies against ovine IgM, IgGi
and Ig light chain were produced and are described fully. IgM and MHC
class II antigens are expressed on the vast majority of IPP cells
whilst cells bearing other serum Ig isotypes and T cell antigens are
rare. A novel Ig molecule appears to be coexpressed with IgM, it is
proposed that this is the ovine equivalent of IgD.IPP cells can be induced to proliferate and differentiate when
cultured with lipopolysaccharide (LPS) and interleukin 2 (IL2).
Proliferation is inhibited by rabbit anti-sheep Ig antibodies. Using an
ELISA for Ig, it has been posible to quantitate Ig synthesis and
secretion. Mean cellular Ig increases greater than 25-fold during
differentiation. High-rate secretion begins 4 days after initiation of
culture and is virtually complete by day 7.As IPP B cells differentiate to IgM secretion, membrane Ig is
rapidly lost so that by day 6, only 15% of cells express Ig en their
surfaces. Changes in MHC class II antigens were also studied. Surface
expression of MHC class II molecules doubled by 24 hours and slowly
declined to resting levels as differentiation proceeded. A large
increase in cytoplasmic MHC class II content was noted on day 3. The
reasons for this inci-ease are discussed
