Reticuloendothelial phagocytic function and antibody formation in gunn rats

Abstract

The reticuloendothelial system (RES) function was determined in Gunn rats by the carbon-gel clearance and the RE 131I lipid emulsion test. Microscopic observations and antigenic stimulation with sheep erythrocytes were also performed. Antibody formation was followed at the cellular and humoral levels by the hemolytic plaque technique and by agglutinin and hemolysin titrations, respectively. Gunn rats have hepatomegaly compared to the parent strain, the Wistar rats. Splenomegaly was only observed in homozygous females. Stimulation of the RES activity, as denoted by increased vascular clearance and hepatic and splenic uptake of the lipid emulsion, was observed in female Gunn rats. Only homozygous females manifested RES stimulation as determined by the carbon method. The RES carbon phagocytic function was normal 7 and 30 days after splenectomy or ovariectomy, respectively. In Gunn rats, the Kupffer cells and splenic follicles appeared hypertrophic. The marginal zone was enlarged and hyperplasia of RE-cells was present in the red pulp. Although similar humoral antibody titers were found, the number of splenic antibody forming cells was greater in Wistar than in Gunn rats. The RES hyperfunction of female Gunn rats seems to be associated with hypersplenic function and probably with a disturbance of estrogen metabolism. The hypertrophy of the lymphoid follicles and hyperplasia of reticulum cells and macrophages in the spleen of Gunn rats did not provide more cells able to respond to antigenic stimulation. In this regard, either fewer antibody-forming cells were sufficient to produce amounts of agglutinin and hemolysin similar to those of Wistar rats, or other areas of the lymphopoietic system compensated for the diminished number of antibody-forming cells in the spleen of Gunn rats.