Antimicrobial Defense Mechanisms in the Salmonella typhimurium Associated Ex-germfree Rat 1

Summary

Germfree rats were monoassociated with Salmonella typhimurium. Early responses included increases in serum α- and β-globulins and a decrease in albumin. A presumably nonimmune γ-globulin fraction of slow electrophoretic mobility showed a similar increase, while carbon clearance values increased 50- to 100-fold. During the second week of association γ-globulin levels increased substantially. This was paralleled by a considerable increase in homologous agglutinating antibody, which first became evident 3 days after association. Both gamma globulin concentration and agglutinating antibody reached a plateau after the second week. At the end of that week, albumin, α- and β-globulin levels, and the carbon clearance index had returned to practically preassociation levels. The nonimmune gamma globulin fraction likewise had regained its preassociation immunoelectrophoretic appearance. It is concluded that while nonspecific defense mechanisms are a major protective factor during the first week after association of the ex-germfree rat, specific antibody production protects the animal during and especially after the second week and enables it to adjust fully to the association with a strongly pathogenic microorganism.