T-cell suppression of human antibody responses: specific or non-specific?

Clinical and immunological results of segmental splenectomy in schistosomiasis

We evaluated segmental splenectomy in 51 patients who required splenectomy to relieve the symptoms of schistosomal splenomegaly, and compared their course with that of 44 patients who underwent total splenectomy in an unrandomized study. We describe a minor modification of our initial technique. Patients having segmental splenectomy had a similar postoperative course to those having total splenectomy. Conversion of a segmental to a total splenectomy was required in two cases due to technical faults. No regrowth of the spleen has occurred in up to 4 years of observation. We noted an increased percentage of T lymphocytes with an increased ratio of T helper to T suppressor cells in patients having segmental splenectomy. Our cumulative experience supports adoption and wider evaluation of segmental splenectomy in schistosomiasis.

Antigen-specific suppression of human antibody responses by allogeneic T cells. II. Cell interactions involved in the generation of suppression

Specific antibody responses to influenza virus were obtained in vitro from human blood mononuclear cells (PBMC). Antibody production in these cultures was profoundly suppressed by the addition of allogeneic T cells with the surface phenotype Leu2a+ (CD8+), Leu8-. Suppression by allogeneic T suppressor (Ts) cells required interactions only between T-depleted B (E-) cells and allogeneic Leu2a+. No evidence was obtained for T-T cell interactions, or for Ts inducer cells similar to those described for nonspecific antibody responses to pokeweed mitogen. Moreover, allogeneic E+, or allogeneic Leu2a+ cells were able to suppress specific antibody responses by E- cells when help was provided by T cell-replacing factor showing that the target of suppression was the responding E- cells, and not T helper cells. In contrast to allogeneic T cells, allogeneic E- cells did not suppress antibody production when added to cultures of unfractionated PBMC (E- + E+). That is, Ts cells activated to allogeneic E- were unable to suppress antibody production by the syngeneic E- cells present in the same culture tube. This result shows that alloactivated Ts cells were specific for the allogeneic E- target cells, and that suppression was not mediated by nonspecific allogeneic effects. Allogeneic Ts cells therefore differ from Ts cells in pokeweed mitogen responses by their specificity, and by their activation in the absence of Ts inducer cells.