Gender and response to antilymphocyte globulin (ALG) for severe aplastic anaemia.

We have evaluated the speed of haematological recovery in 103 severe aplastic anaemia (SAA) patients treated with antilymphocyte globulin (ALG) and followed at our institution for 3-15 years. We found that haemopoietic recovery was significantly delayed in six girls under the age of 10 years. This slow recovery in girls might be explained by their relative inability to release haemopoietic growth factors, granulocyte colony stimulating activity and burst promoting activity, compared to all other sex and age groups. This defect is not explained by disease severity at presentation and thus indicates a functional abnormality of monocytes/macrophages and T-lymphocytes in addition to the deficiency of haemopoietic stem cells. In a multivariate analysis, low factor production and low pretreatment reticulocyte counts turned out to be strong predictors of slow haemopoietic recovery. We conclude that young girls have a particular form of SAA characterized by low haemopoietic factor production and delayed recovery after ALG. They are preferential candidates for early bone marrow transplantation or, if they are not eligible, for treatment with recombinant human haemopoietic growth factors.