RESUMO
The in vitro immune functions of peripheral blood lymphocytes have been studied in 12 children with beta-thalassaemia major and hypersplenism. The study was performed prior to splenectomy and on the 2nd, 6th, 15th and 30th day after splenectomy. It was found that before splenectomy, patients had low numbers of blood leucocytes, normal rosette and T3 lymphocyte counts, low T4 and normal T8 lymphocyte counts with a T4/T8 ratio below 2, impaired T lymphocyte mitogenic responses induced by PHA, increased numbers of polyvalent and monovalent B lymphocytes and normal immunoglobulin levels of IgG and IgA. After splenectomy, especially on the 2nd day, leucocytosis, a significant decrease of T cells and their subsets and a reduction of the IgM levels were found. These parameters, except the IgM levels, increased until the 30th day after splenectomy and reached presplenectomy values. On the 2nd day after splenectomy, large mononuclear cells behaving like immunocytes appeared in the peripheral blood. They had the phenotype of T3, T4, T8, B lymphocytes and OKM1 monocytes. All the large mononuclear cells increased significantly on the 6th day after splenectomy and remained elevated during the whole study (30 days). The T4/T8 ratio was increased, but no increase was found in the functional responses of T lymphocytes.
