Bone marrow immunoglobulin-secreting cells are not reduced in children with leukaemia as compared to children with...

Children with leukaemia exhibit multiple immunological disturbances, including low circulating levels of immunoglobulins, caused by both the disease and chemotherapy. We investigated the number of isotype-specific immunoglobulin-secreting cells (ISCs) in the bone marrow at the time of diagnosis in 32 children and during therapy in 12 children with leukaemia. We compared these to the number of ISCs in 17 untreated children with solid tumours and related the ISCs to serum immunoglobulin levels, lymphocyte subsets, response to mitogenic stimulation and serum cytokine levels. Bone marrow specimens were analysed for isotype-specific (immunoglobulins G, A and M) ISCs using the ELISPOT method. At the time of diagnosis, for all isotypes, the total number of ISCs per millilitre of bone marrow in children with leukaemia was no different from that in children with solid tumours. Chemotherapy significantly decreased the number of ISCs. The quantitative relationship between the different isotypes was unaffected by both tumour type and therapy. It can be concluded that in childhood leukaemia, tumour replacement of bone marrow cells does not cause a decreased number of ISCs and can therefore not account for the low serum immunoglobulin levels observed at time of diagnosis. Chemotherapy reduces the number of ISCs without changing the isotype distribution.