BONE-MARROW IMMUNOGLOBULIN-SECRETING CELLS ARE NOT REDUCED IN CHILDREN WITH LEUKEMIA AS COMPARED TO CHILDREN WITH SOLID TUMORS

Children with leukaemia exhibit multiple immunological disturbances, i ncluding low circulating levels of immunoglobulins, caused by both the disease and chemotherapy. We investigated the number of isotype speci fic immunoglobulin-secreting cells (ISCs) in the bone marrow at the ti me of diagnosis in 32 children and during therapy in 12 children with leukaemia. We compared these to the number of ISCs in 17 untreated chi ldren with solid tumours and related the ISCs to serum immunoglobulin levels, lymphocyte subsets, response to mitogenic stimulation and seru m cytokine levels. Bone marrow specimens were analysed for isotype-spe cific (immunoglobulins G, A and M) ISCs using the ELISPOT method. At t he time of diagnosis, for all isotypes, the total number of ISCs per m illilitre of bone marrow in children with leukaemia was no different f rom that in children with solid rumours. Chemotherapy significantly de creased 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 bo ne marrow cells does not cause a decreased number of ISCs and can ther efore not account for the low serum immunoglobulin levels observed at time of diagnosis. Chemotherapy reduces the number of ISCs without cha nging the isotype distribution.