EB-virus-specific IgM and IgG antibodies in first-degree relatives of children with acute lymphoblastic leukaemia.

EB-virus-specific IgM and IgG antibodies (to virus capsid and soluble complement fixing antigens) were estimated in sera from mothers and sibs of children with acute lymphoblastic leukaemia, from patients with infectious mononucleosis, and from control induviduals. IgM antibodies were present in 12 of 16 mothers and 3 of 4 sibs of children with acute lymphoblastic leukaemia. They were also present in 14 of 16 patients with infectious mononucleosis, but in only 1 of 12 control individuals.