THYMIC FUNCTION IN ADULTS - EVIDENCE DERIVED FROM IMMUNE RECOVERY PATTERNS FOLLOWING MYELOABLATIVE CHEMOTHERAPY AND STEM-CELL INFUSION

We studied 45 patients aged 14-66 years who had undergone stem cell. t ransplantation for a variety of malignant conditions at least 12 month s previously. Compared to normal controls, they had significantly redu ced absolute numbers of CD4(+), CD4(+)CD45RA(+) and CD4(+)CD45RO(+) T cells and a reduced CD4(+)CD45RA(+):CD4(+)CD45RO(+) ratio. In all subs ets T-cell numbers were significantly greater 24 months, compared to 1 2-24 months, after transplantation and there was a nonsignificant tren d towards lower T-cell numbers with increasing age. We conclude that t he thymus, or putative thymic-equivalent tissue, remains functional in older adults.