An immunological study during post-transplantation follow-up of a case of severe combined immunodeficiency.

A 5-month-old boy with severe combined immunodeficiency treated 2 years ago by transplantation of a foetal thymus and bone marrow-derived cells from a 7-year-old sister, now shows complete clinical recovery. The first indication of activity of the cellular immune system appeared 1 week after transplantation, and in the humoral immune system during the 3rd week. By 18 months all laboratory findings were comparable to those in a normal boy, except that all the PHA-stimulated peripheral blood lymphocytes showed an XX karyotype. The sequence of appearance of individual immunoglobulin classes, subclasses, and types, transitory appearance of at least three homogenous immunoglobulin components (`paraproteins'), the close relationship between an increase of immunoglobulin-containing cells in the blood and the corresponding rise in serum immunoglobulin levels, and the relationship between secretory and serum IgA are reported.