Alternative Potentiating and Inhibitory Effects of GVH Reaction on Formation of Antibodies Against a Thymus-Independent Polysaccharide (SIII)

Abstract

Abstract The direct PFC response to SIII (type 3 pneumococcal polysaccharide) has been studied in adult (C57BL × CBA-T6T6) F1 mice in which graft-vs-host (GVH) reaction was induced by parental strain lymphoid cells. The response was potentiated for 3 to 6 days after injection of lymphoid cells when SIII was injected either separately or coupled to the cells. An analysis of this effect revealed: a) that it requires recognition of the host by viable donor thymus-derived (T) lymphocytes and their subsequent proliferation (the reverse, host-vs-graft, situation was ineffective); and b) that it seems to be attributable to a different T cell function than that responsible for specific “helper” activity. On the other hand, F1 mice examined 6 to 109 days after injection of 8 × 107 parental spleen cells were totally unresponsive to SIII. Furthermore, there was no response to SIII in lethally irradiated mice repopulated with spleen cells from GVH animals or with a mixture of GVH and normal spleen cells. Treatment of the GVH cells with anti-ϑ serum partially alleviated this suppressive effect. We conclude that potentiation and suppression are both attributable to T cell activity, and that they seem to differ qualitatively rather than quantitatively. Macrophages may be involved in an intermediary effector capacity in the suppressive phenomenon.