Encephalitogenic T lymphocytes develop from SJL/J hematopoietic cells transplanted into severe combined immimodeficient ( SCID) mice

Previously, we constructed chimeras by injecting hematopoietic cells from experimental autoimmune encephalomyelitis (EAE)-susceptible SJL (H-2^S) strain mice into severe combined immunodeficient (SCID) C.B-17scid /scid (H-2^d) mice. These SCID mouse-SJL mouse hematopoietic cell chimeras developed passive EAE following adoptive transfer of PLP S139-151-specific SJL T lymphocyte line cells, but were resistant to active EAE induced by primary immunization with PLP S139-151. In order to gain an understanding of the encephalitogenic potential of transplanted hematopoietic progenitors in SCID mouse-SJL mouse chimeras, we attempted to induce EAE in hematopoietic chimeras constructed with or without an additional SJL fetal thymus implant. Chimeras with the thymus implant were susceptible to passive and active EAE while chimeras without the thymus implant were susceptible to passive but not active EAE. Encephalitogenic, CD4⁺, TCR⁺ T lymphocytes were selected in vitro from PLP S139-151-immunized, thymus-implanted chimeras. These results showed that hematopoietic SJL progenitors developed into antigen-presenting accessory cells and immunocompetent encephalitogenic T lymphocytes following transplantation into SCID mice. The development of primary immune reactivity depended on a fetal thymus implant for expression in SCID mouse-SJL mouse chimeras.