PRESENCE OF HOST-SPECIFIC INTERLEUKIN 2-SECRETING T-HELPER CELL PRECURSORS CORRELATES CLOSELY WITH ACTIVE PRIMARY AND SECONDARY CHRONIC GRAFT-VERSUS-HOST DISEASE

We investigated the role of interleukin 2 (IL-2)-secreting T helper ce ll precursors (Th-p) in primary and secondary chronic graft-versus-hos t disease (GVHD), Twelve patients with chronic GVHD (8 primary and 4 s econdary chronic GVHD) and 8 patients without chronic GVHD were invest igated using a sensitive limiting dilution assay, High frequencies of host-reactive interleukin 2-secreting T helper cell precursors were de tectable in all patients with chronic GVHD irrespective of the mode of onset, Host-reactive IL-2-secreting T helper cell precursors disappea red in patients whose GVHD resolved. Host-reactive IL-2-secreting T he lper cell. precursors were never found in the control patients without chronic GVHD, Host-reactive cytotoxic T cell precursors (CTL-p) were not consistently detectable in patients with chronic GVHD and were occ asionally found in patients without GVHD. No autoreactive IL-2-secreti ng T helper cell precursors or cytotoxic T cell precursors were detect able in either group. The absence of autoreactive IL-2-secreting T hel per cell precursors in patients was confirmed by clonal specificity an alysis in 4 patients, These data suggest a role for host-reactive IL-2 -secreting T helper cell precursors In the initiation and maintenance of chronic GVHD as previously shown for acute GVHD.