Modification of suppressor/cytotoxic and helper subsets in lentil lectin-pretreated mice

The effect of lentil lectin (LCA) on various lymphocyte subpopulations in the spleen, lymph nodes and thymus of CBA mice was studied. The most marked effect after five 1-mg LCA doses was observed in the spleen. LCA caused a drop in both the total and relative number of cells carrying all the markers examined, i.e., Thy 1, L3/T4a, Lyt 2, and sIg, so that large numbers of lymphocytes did not express any of them. A dramatic decrease in the Thy 1-positive cell number is mainly due to depletion of the L3/T4a (helper) T cell subpopulation, whereas the Lyt 2 + (suppressor/cytotoxic) cells are less affected. The decrease in the Thy 1 + , Lyt 1 + and L3/T4a + cell numbers in the thymus and lymph nodes is smaller, the percentage of Lyt 2 + cells is even increased after LCA treatment. Our results indicate that two mechanisms play a role in the induction of allotransplantation tolerance by LCA: (a) ‘depletion’ of helper T cells and (b) a relative increase in the regulatory (suppressor) cell ratio, which may support allograft survival.