Background: Cancer and its treatment are a major cause of secondary immunodeficiency in childhood. Leukaemias are the most frequent pediatric neoplastic diseases and 80 % are lymphoblastic (ALL). The objectives of this study are to describe the epidemiology of children with ALL in our hospital and to analyse the evolution of immunoglobulins' concentration at leukaemia's onset, during its treatment and after finishing it.
Methods and results: Retrospective study of patients with ALL treated with the SHOP-LAL-94 protocol. 50 patients were studied. Patients were classified in three groups: ALL- cell line B, ALL-cell line B with relapse, and ALL-cell line T. We analysed clinical data and laboratory results (IgG, IgA and IgM concentration) at leukaemia's onset, during its treatment and until 12 months after it.1. ALL-B: 44 patients. At the onset all patients, but a newborn with congenital leukaemia, had normal immunoglobulins. During treatment there was a significant decrease in immunoglobulins'concentration, being IgM the most affected (65 % of patients), followed by IgG (53 % of patients). The mean normalization time of immunoglobulins was 12 months.2. ALL-B with relapse: 7 patients. At relapse 2 patients had an IgM deficit and 1 overall immunoglobulin deficiency. During treatment there was a decrease in all immunoglobulins, which was significant for IgG. IgG and IgM decreased in all patients during relapse's treatment. There were 5 deaths, all with IgM < 186 mg/L.3. ALL-T: 6 patients, one died 3 days after diagnosis. At the onset all patients had normal immunoglobulins. Two patients had a favourable evolution, having a decrease in immunoglobulins'concentration during treatment, significant for IgM, with normalization 6 months after treatment. The rest 3 patients relapsed and died, having a global immunoglobulins'deficit during treatment and previous to death.
Conclusions: At ALL's onset immunoglobulins' concentration is normal. During treatment the majority of patients have immunoglobulins' deficiency, being IgG and IgM the most affected immunoglobulins. A persistent IgM deficit is associated in our series with a higher risk of relapse and death. In patients with a good outcome immunoglobulins normalize before one year after treatment.