X-LINKED SEVERE COMBINED IMMUNODEFICIENCY WITH GAMMA-DELTA-T CELLS

A patient with X-linked severe combined immunodeficiency (X-SCID) was found to have a deletion mutation of a four base pair in the transmemb rane domain of the IL-2 receptor gamma chain gene, a subunit shared by the receptors for IL-4: IL-7, IL-9. and IL-15 (common gamma chain; ga mma c). He had very few alpha beta T cells but had a considerable numb er of gamma delta T cells in his peripheral blood. Fluorescence in sit u hybridization (FISH) analysis showed that the gamma delta T cells in his peripheral blood were not of maternal origin. He had received a B acillus Calmette-Guerin (BCG) vaccination before recognition of the di sease, and the BCG infection remained quiescent with no reaction for 1 9 months. After successful bone marrow transplantation, the site of th e BCG vaccination showed a reaction. and live BCG were detected. It is useful to consider the relationship between the existence of gamma de lta T cells and BCG in this case, and it is suggested that gamma delta T cells may be, in a given situation, less dependent on the gamma c c hain than are alpha beta T cells.