Severe combined immunodeficient mice engrafted with macaque peripheral blood leukocytes support replication of SIVsmm

Human and Nonhuman Primate Lymphocytes Engrafted into SCID Mice Reside in Unique Mesenteric Lymphoid Structures

The present study compares the location and phenotype of B lineage lymphocytes in tissues from SCID mice engrafted with PBMC of human, chimpanzee, and pig-tailed macaque origin. In mice repopulated with both human and nonhuman primate lymphocytes, plasma cells were found in the peritoneal cavity in vascularized structures located in the mesentery near the pancreas, intestines, and spleen. The predominant isotype of the plasma cells was IgG; IgM and IgA cells were also present. κ and λ light chains were expressed by 62% and 38% of the Ig-containing cells, respectively. J chain expression occurred in most cells irrespective of the Ig isotype. In the SCID mice engrafted with human lymphocytes, a few IgM-containing cells were found in the spleen; plasma cells were not found in other tissues, including the intestine. The aggregation of plasma cells did not appear to be a result of infection with EBV. T cells were rarely found in the lymphoid aggregates but were recovered from the spleen and peritoneal lavage. Human Ig levels in the serum of engrafted mice reflected the isotype distribution of the cells with IgG > IgM ≥ IgA.

HIV-1/Simian Immunodeficiency Virus Infection of Human and Nonhuman Primate Lymphocytes Results in the Migration of CD2+ T Cells into the Intestine of Engrafted SCID Mice

Increased lymphocytic infiltration of intestinal tissues has been observed in patients infected with HIV-1 and in SIV-infected rhesus macaques. To determine whether HIV-1 and SIV infections influence the homing of human and nonhuman primate PBMC to intestinal tissues, we engrafted SCID mice with human or nonhuman primate PBMC and infected them with either cell-free or cell-associated HIV-1 or SIV. In mice that received both PBMC and virus, human or nonhuman primate CD2+ T cells were found in intestinal tissues, primarily in the intraepithelial lymphocyte compartment and lamina propria. Immunomagnetic sorting revealed that these cells were derived from the CD4+ population. Using gag-specific primers, PCR analysis of these tissues detected the presence of HIV-1 proviral DNA. However, in SCID mice that were engrafted with either human or nonhuman primate PBMC and no HIV-1 or SIV, CD2+ T cells were not detected in intestinal tissues. These results indicate that HIV-1 and SIV can modulate the migratory properties of human and nonhuman primate T cells in the SCID mouse model.