The effects of anti-theta-globulin treatment on the morphology of the mouse spleen.

Rabbit anti-mouse-theta-globulin raised against the brain tissue of DBA/2 mice was injected into DBA/2 mice subcutaneously 4 times at 2 days intervals and the histology of the spleen was assessed 1, 2, 4, 7, 14 and 21 days after the last dose. Untreated animals and those treated with normal rabbit gammaglobulin were used as controls. Anti-theta-globulin was found to induce a profound depletion of the small lymphocytes in the central regions of the periarterial lymphoid sheath (C-PALS). At the same time, a strong stimulation of the cellular elements involved in antibody response was evident in the peripheral regions of the periarterial lymphoid sheath (P-PALS). This stimulation was even more pronounced in mice treated with normal rabbit gammaglobulin, a fact possibly due to the undisturbed T-B-cell interaction in these cases. The results support the concept that two distinct areas exist in the spleen white pulp, C-PALS and P-PALS, a thymus- and a bursa-dependent area, respectively. A standardized system, analogous to that previously proposed for the morphology of the lymph nodes by Cottier et al. (1973), was introduced to describe the morphology of the spleen white pulp in relation to the immunological function.