Delayed hypersensitivity to Staphylococcus aureus in mice: kinetics of induction.

The induction of systemic delayed hypersensitivity to is dependent on a minimum of two weekly injections of viable bacteria. lymphocyte stimulation studies show that the spleen acts as a repository for the immunogen-responsive lymphocytes associated with DH. To evaluate the kinetics of induction, mice were given one to three weekly injections of viable and the weights, lymphocyte numbers, DNA synthesis and lymphocyte immunogen reactivity of the draining lymph node (DLN), contralateral lymph node (CLN), and spleen (SP) were determined at days 7, 14 and 21 post injection. The staphylococcal immunogens included whole cell sonicate, cell wall, cell membrane, protein A, lipoteichoic acid, teichoic acid and purified membrane proteins. A single injection resulted in an increase in organ weight, lymphocyte numbers and DNA synthesis of the DLN. This was accompanied by lymphocyte responsiveness to all immunogens. There was an increase in spleen weight and lymphocyte numbers without an appreciable increase in DNA synthesis. Spleen lymphocytes showed no increase in immunogen responsiveness. A second injection maintained the increased weight, lymphocyte numbers and DNA synthesis of the DLN but resulted in a suppression of lymphocyte responsiveness to all immunogens. Splenic lymphocytes showed reactivity to all immunogens. This was accompanied by an increase in lymphocytes and mitogenic responsiveness without mitosis. The third injection maintained suppression of DLN cells and further stimulated those of the spleen. The splenic lymphocytes were hyper-reactive to B-lymphocyte and T-lymphocyte mitogens and showed an increased rate of DNA synthesis.