Clonal analysis of the T lymphocytes involved in parent versus F1 graft-versus-host reaction.

A systemic graft-versus-host reaction (GVHR) leading to 50% mortality by day 20 was elicited by the injection of CBA (10(5)) or B10 (10(6)) parental T lymphocytes into irradiated (750 rad) and bone marrow protected (CBA X B10)F1 recipients. Between days 12 and 28 the spleens of the sick mice were analyzed by limiting dilution, performed with irradiated F1 cells and a source of interleukin-2 (IL-2), to determine the frequency of cells with an antihost proliferative or cytolytic activity and to derive T lymphocyte clones. The frequency of cells with antihost proliferative or cytolytic activity was approximately 10(-3) in either combination. In the CBA vs F1 GVHR, all eight clones isolated with anti-F1 activity were Lyt-2-, noncytolytic, mixed lymphocyte reaction (MLR) responders and IL-2 producers, three of which mapped to the Ab locus, while in the B10 anti-F1 combination, eight of the nine anti-F1 clones isolated were Lyt-2+, poor MLR responders and non-IL-2 producers, but cytolytic and mapping to Kk. These findings suggest a much higher frequency of T cells recognizing the A-locus antigens in the CBA than in the B10 strain.