[Evaluation of selected parameters of specific immunity in children with osteosarcoma at various stages of antitumour treatment].

Unlabelled: Typical cells of specific immunity are lymphocytes. T cells may specifically recognize antigens using T Cell Receptors (TCRs). Antigen presentation by specialized cells is a necessary element of specific immunity. It leads to initiating an immune response. After antigen dependent activation T cells transform to memory and effector lymphocytes. Cells engaged directly in destruction of the tumour are CD8+cytotoxic T lymphocytes, CD4+ lymphocytes, Tγδ lymphocytes, NK, NKT cells and indirectly B lymphocytes. One of the main methods of osteosarcoma treatment in children is chemotherapy. The goal is to destroy the cancer cells by putting them in a state of apoptosis. All of the medications used as chemotherapy carry the risk of short-term and long-term problems including leukopenia, immune disorders such as immunodeficiency.

The Aim Of Study: was evaluation by flow cytometry selected elements of specific cellular immunity in children with osteosarcoma at various stages of antitumour treatment.

Materials And Methods: The study was performed on the group of 44 children with osteosarcoma, aged from 6 to 20 years (average 14.9 years; median 15.0 years). T and B lymphocytes and subpopulations: CD4+, CD8+, CD3+?HLA-DR+, CD3+γδ; NK, NKT cells were analyzed in peripheral blood with use of flow cytometry method with monoclonal antibodies. Examinations were performed before the therapy - in diagnostic period (examination I), after the neoadjuvant chemotherapy (examination II), 10-14 days after the surgery (examination III), 5 months after the surgery (after adjuvant chemotherapy, examination IV).

Results: The number of T and B lymphocytes was decreasing after each stage of cytostatic therapy, with the biggest differences for CD19+ cells (medians: I examination - 205.0; II exam. - 62.0; IV exam. - 24.0 cells/mL); in single cases the number of cells decreased even under 10/mL (norm 200-500 cells/mL).

Conclusions: 1. In children and youth with osteosarcoma antineoplastic treatment contributes to the suppression of the immune system, decreasing definitely the number and percentage of B lymphocytes, T helper lymphocytes and NK cells. 2. Decreased number of CD3+, CD4+, CD19+ and NK lymphocytes during chemotherapy may contribute to the progression of neoplastic disease in the future, after treatment. 3. Evaluation of immunologic status in patients with osteosarcoma may be helpful in monitoring of antineoplastic therapy effectiveness, may prevent the formation of unfavourable clinical changes and may be the basis for correction of the cytostatic agents' administration.