Polyclonal hypergammaglobulinemia at the onset of acute myeloid leukemia in children

Polyclonal hypergammaglobulinemia (PHG) associated with hematological malig nancies is a rare occurrence. We reviewed our series of 47 children with AM L in order to define the prevalence of PHG and its prognostic value in achi eving complete remission (CR) after induction treatment. Patients were stra tified by immunoglobulin levels into two groups: with PHG and without PHG. CR reached after induction chemotherapy was considered a positive response. Conditional exact tests were used for the statistical analysis; conditiona l maximum likelihood estimates of the odds ratio (OR) were obtained. Signif icance levels (p) were determined from two-tailed tests. Twenty-two of 38 ( 57.9%) evaluable children showed PHG. Children with PHG and AML were more l ikely to be in CR after first induction treatment (OR=6.25, p=0.021), indep endent of sex, age at diagnosis, white blood cell count, percentage of blas ts in the bone marrow, FAB phenotype, and treatment protocol. Infections se emed to positively influence early treatment response (p=0.038), PHG and in fections were not statistically associated (p=0.16). PHG may result from th e uncontrolled stimulation of B lymphocytes by cytokines, Infections or tra nsfusions may act as triggers for the immune system, leading to the antileu kemic effect seen in patients with AML and PHG going into spontaneous remis sion. It could be that this activation caused the larger number of CRs obse rved in our series. Clarification of why PHG exerts a positive influence on children with AML could help us to understand the ways by which the organi sm is able to control a malignant disease.