T Cell Lymphoma and Leukemia in Severe Combined Immunodeficiency Pigs following Bone Marrow Transplantation: A Case Report

Abstract

After the discovery of naturally occurring severe combined immunodeficiency (SCID) within a selection line of pigs at Iowa State University, we found two causative mutations in the Artemis gene: haplotype 12 (ART12) and haplotype 16 (ART16). Bone marrow transplants (BMTs) were performed to create genetically SCID and phenotypically immunocompetent breeding animals to establish a SCID colony for further characterization and research utilization. Of nine original BMT transfer recipients, only four achieved successful engraftment. At approximately 11 months of age, both animals homozygous for the ART16 mutation were diagnosed with T cell lymphoma. One of these ART16/ART16 recipients was a male who received a transplant from a female sibling; the tumors in this recipient consist primarily of Y chromosome-positive cells. The other ART16/ART16 animal also presented with leukemia in addition to T cell lymphoma, while one of the ART12/ART16 compound heterozygote recipients presented with a nephroblastoma at a similar age. Human Artemis SCID patients have reported cases of lymphoma associated with a “leaky” Artemis phenotype. The naturally occurring Artemis SCID pig offers a large animal model more similar to human SCID patients and may offer a naturally occurring cancer model and provides a valuable platform for therapy development.

Novel engraftment and T cell differentiation of human hematopoietic cells inArt-/-IL2RG-/SCID pigs

“…We previously described the discovery of naturally occurring Art -/- SCID pigs 3 , which we have been able to raise and breed 14,32 for research purposes. We started with this genetic background for IL2RG site-directed mutagenesis.…”

“…A total of 2.27 x 10 8 million unfractionated bone marrow cells from the ribs and sternum were collected and administered to one Art -/- IL2RG -/ Y SCID pig. The piglet was not conditioned prior to the BMT, based on our previous success with porcine T and B cell reconstitution without conditioning in Art -/- SCID pigs 32 .…”

“…The Art12 allele contains a nonsense mutation in exon 10, while the Art16 allele contains a splice site mutation in intron 8 3 . Frozen semen from a bone marrow transplanted (BMT) rescued Art12 / 16 32 boar was utilized to artificially inseminate two Art +/- carrier sows. The sows were sacrificed at day 35 of gestation and fetuses were collected in a sterile manner to obtain fetal fibroblasts (pFF), as described previously 62 .…”

“…Upon reaching 100% confluence, the pFF cells were trypsinized, frozen in FBS with 10% dimethyl sulfoxide (DMSO) and stored long-term in liquid nitrogen. Simultaneously, cellular DNA was sent for SLA typing, as described in Powell et al 32 . SRY and Artemis primers (Supplemental Table 6) were utilized to identify pFF sex and Artemis genotype 3 .…”

CD3ε+ Cells in Pigs With Severe Combined Immunodeficiency Due to Defects in ARTEMIS

“…Upon the discovery of the ART SCID pigs, bone marrow transplantation (BMT) was performed to reconstitute the animal immune system and to further study the animals. Among the SCID pigs that underwent BMT, two ART16/16 pigs developed host derived CD3ε + Tcell lymphoma (3). This led us to hypothesize that the ART16 allele potentially produced Artemis protein with residual activity, resulting in development of T cells.…”