PHENOTYPIC AND FUNCTIONAL-EVALUATION OF NATURAL-KILLER-CELLS IN THYMECTOMIZED CHILDREN

The purpose of this study was to determine the effect of thymectomy on the number and activity of NK cells in the peripheral blood of childr en submitted to thymus removal. Twenty-three children, aged 4 to 48 mo nths at thymectomy, whose thymus was fully removed to permit access to the heart for corrective surgery, were studied. Only children thymect omized during the first year of life had a decreased number of CD2(+)/ CD3(+), CD4(+)/CD16(-), and CD8(+)/CD16(-) T subsets and an increase i n the CD16(-)/CD56(bright+) NK subset. In addition, the CD57(-)/CD16() and CD57(-)/D56(+) subsets which are shared by T and NK cells were i ncreased. These findings associated with a tendency to increased Nh ac tivity suggest that the human thymus is partially involved in the cont rol of the release of circulating T cells and may negatively modulate some NK subsets, as well as NK activity, during the first year of life but not later. (C) 1996 Academic Press, Inc.