Isoelectric heterogeneity of immunoglobulin secreted by LPS-activated neonatal and adult pig lymphocytes in vitro.

The heterogeneity of immunoglobulin secreted by lymphocytes from neonatal presuckled and from adult pigs after Acinetobacter lipopolysaccharide (LPS) activation has been examined by isoelectric focusing and two-dimensional electrophoresis. LPS activation of neonatal and adult cells resulted in secretion of IgM immunoglobulins which were closely similar in their degree of isoelectric heterogeneity. Immunoglobulins secreted by both types of cell after LPS activation were also very similar in their heterogeneity to that secreted by control unstimulated adult cells. LPS therefore appears to be acting polyclonally, with no preferential stimulation of particular spectrotypes. Cell populations from neonatal pigs are antigenically naive and thus devoid of B memory cells: after LPS activation the IgM secreted by neonatal cell preparations was closely similar in its heterogeneity to that secreted by adult cells. Two dimensional electrophoresis has resolved two light chain types (kappa and gamma analogues) in the immunoglobulin secreted by neonatal and adult cells, with a common pattern of light chain spectrotypes underlying individuality in the balance of constituent spectrotypes between different cell samples.