Background. sHLA molecules are the soluble forms of their membrane bound counterparts. sHLA class I. were recently reported to be a useful marker in the prediction of graft versus host reaction (GVHR) in adults. To confirm these presumptions in children we measured sHLA class I. serum levels in children after allogeneic bone marrow transplantation (BMT). We also investigated the levels of sHLA in the supernatants of mixed lymphocyte cultures (MLC) as possible predictors of GVHR prior to BMT. Methods and Results. Group of 6 investigated children included 1 child with severe combined immunodeficiency, 3 children with acute lymphoblastic leukemia, 1 with severe combined immunodeficiency, 3 children with acute lymphoblastic leukemia, 1 with severe aplastic anemia and 1 with non Hodgkin lymphoma. The period of follow up varied from 15 days to 21 months according to the course of the disease. In the prediction of GVHR the levels of sHLA were measured in 5 children with acute leukemia in supernatants of MLC and the results were compared with the grade of GVHR classified according Seattle criteria. Soluble HLA class I. molecules were evaluated by ELISA. Rise of the levels of sHLA preceded 1-2 days the clinical signs of GVHR, however, it could not be distinguished from the occasional rise of a different cause. The levels of sHLA found in the supernatants of MLC showed individual results, which did not correspond to the level of cytokines in the same culture, or to the grade of GVHR observed. However, twice higher levels of sHLA in the culture of donor lymphocytes correlated with the lethal outcome of GVHR despite the fact that the donors were HLA identical siblings. Conclusions. The usefulness of sHLA levels as the predictors of GVHR has to be interpreted with great caution, but they can be used as a part of the mosaic composed of the clinical image and other laboratory results indicating GVHR. The predictive value of sHLA in supernatants of MLC is still to be evaluated.

        Key words: HLA antigens, bone marrow transplantation, graft vs host disease.