45 SPECIFIC IMMUNE CAPACITY IN CHILDREN WITH APLASTIC ANEMIA

The specific immunological capacities in 32 children, suffering from aplastic anemia were investigated at the time of diagnosis. The mean number of bloodlymphocytes was low i.e. 1.9 × 109/l; several patients had a lymphocytopenia. In 16 patients lymphocyte subpopulations in the peripheral blood were investigated: the absolute numbers of T cells were within the normal range; the absolute numbers of B cells were low. The serumimmu-noglobulin levels for the different Ig classes were within the normal range. The in vitro response of bloodlymphocytes following stimulation with PHA and ALS, and following stimulation with allogeneic cells was normal. In contrast, the response of blood-lymphocytes to PWM and Con-A was significantly (α <0.05) dedreased, as was the stimulatory capacity in the MLC, in comparison with normal controls. In 13 children treated for their severe aplastic anemia with bone marrow transplantation these in vitro lymphocyte responses to mitogens were significantly (α <0.05) decreased in comparison with the data from their MLC identical bone marrow donors. A positive correlation between these findings and the absolute numbers of monocytes in the blood and in the in vitro cultures was found. An indication was present for a possible relationship between some of the immunological findings and the course of children with aplastic anemia, either on medical treatment or after bone marrow transplantation.