Abstract • 82

Background: Swedish children are vaccinated against measles, mumps and rubella (MMR) at 18 months of age with a booster at 12 years. 98% of vaccinated children have been shown to have neutralising antibodies against measles before the booster. The aim of this study was to analyse the B-cell memory repertoire through measurement of antibodies against MMR in children treated for acute lymphatic leukaemia (ALL).

Patients and methods: Twenty-eight children (14 men), (median (range)) 13 (9-24) years of age, in complete remission, treated according to the Nordic protocol for ALL during the period of 1987-1992 were included in the study. None of the children received radiotherapy. Blood samples for the analysis of MMR were obtained 8 (5-10) years after completed treatment. Data regarding vaccination before and after completed treatment was obtained by questionnaire.

Results: In the children vaccinated against MMR, antibodies after treatment were lacking against MMR in 29% (8/28), 35% (10/28) and 21% (6/28) of the subjects, respectively.

Conclusion: Our results indicate that a high proportion of children treated for ALL have lost their capacity to produce functional antibodies against MMR. These children are at risk of developing active MMR and may act as a reservoir for MMR in the community.