Phenotypic Analysis of New World Primate Mononuclear Cell Surface Antigens

Hematopoietic activity of common marmoset CD34 cells isolated by a novel monoclonal antibody MA24

OBJECTIVE

We focused on a small New World monkey, the common marmoset (Callithrix jacchus), to establish a nonhuman primate model of the treatment of hematological disorders. In this study, we developed the first monoclonal antibodies (MAbs) against marmoset CD34 and tested the in vitro and in vivo hemopoietic activity of cell populations isolated using one of these MAbs.

METHODS AND RESULTS

Marmoset cDNA encoding a human CD34 homologue was cloned from bone marrow (BM)-derived RNA using reverse transcription polymerase chain reaction and rapid amplification of cDNA ends. The amino acid sequence of the marmoset CD34 had 81% homology with the human sequence. Five mouse MAbs were raised against marmoset CD34 transfectant. One representative MAb, MA24 (IgM), reacted with approximately 0.5 to 1% of BM mononuclear cells (MNCs), where the colony-forming unit granulocyte/macrophage (CFU-GM) was enriched approximately 11- to 75-fold as compared with the whole BM MNCs. Multilineage differentiation of marmoset CD34+ cells in NOD/SCID mice was confirmed by flow cytometry 1 month after xenotransplantation.

CONCLUSION

These results demonstrated that MA24 is useful for the analysis and enrichment of hematopoietic progenitor cells in the marmoset model for preclinical experiments.

Haematopoietic progenitor cells from the common marmoset as targets of gene transduction by retroviral and adenoviral vectors

To establish a new non-human primate model for human cytokine and gene therapy, we characterized lymphocytes and haematopoietic progenitor cells of the small New World monkey, the common marmoset. We first assessed the reactions of marmoset bone marrow (BM) and peripheral blood (PB) cells to mouse anti-human monoclonal antibodies (mAbs) for the purpose of isolating marmoset lymphocytes and haematopoietic progenitor cells. Both cell fractions stained with CD4 and CD8 mAbs were identified as lymphocytes by cell proliferation assay and morphological examination. Myeloid-specific mAbs such as CD14 and CD33 did not react with marmoset BM and PB cells. No available CD34 and c-kit mAbs could be used to purify the marmoset haematopoietic progenitor cells. Furthermore, we studied the in vitro transduction of the bacterial beta-galactosidase (LacZ) gene into CFU-GM derived from marmoset BM using retroviral and adenoviral vectors. The transduction efficiency was increased by using a mixed culture system consisting of marmoset BM stromal cells and retroviral producer cells. It was also possible to transduce LacZ gene into marmoset haematopoietic progenitor cells with adenoviral vectors as well as retroviral vectors. The percentage of adenovirally transduced LacZ-positive clusters was 15% at day 4 (multiplicity of infection=200), but only 1-2% at day 14. The differential use of viral vector systems is to be recommended in targeting different diseases. Our results suggested that marmoset BM progenitor cells were available to examine the transduction efficiency of various viral vectors in vitro.

Comparative study on age-dependent development of surface receptors on peripheral blood lymphocytes in children and young nonhuman primates (marmosets)

General conformity was found concerning age-dependent changes in the major subsets (CD4, CD8, CD2, CD20) and the adhesion molecules CD11a and CD29 on peripheral blood lymphocytes in children and young marmosets (Callithrix jacchus). Differences exist in the expression of the surface receptors CD45RA and CD56. Taking the total number of white blood cells into account, an age-related increase in the absolute numbers of peripheral blood lymphocytes was found in marmosets whereas in children, an age-dependent decrease was observed. The definition of reference ranges for different stages of maturation in children and young marmosets may serve as a basis on which comparative risk assessment of possible effects on lymphocyte subsets after pre- or perinatal drug exposure can be estimated.

Evaluation of anti-human antibodies for immunohistochemistry on archival nonhuman primate tissues

A panel of commercially available antibodies which recognize specific antigens on human tissues was developed for use in immunohistochemistry on tissues from eight species of nonhuman primates. Antibodies were selected for potential usefulness in diagnostic pathology, and for effectiveness in formalin-fixed, paraffin-embedded tissues. Tissues from four species of macaques and four New World monkeys were evaluated. Using these antibodies we were able to identify 17/21 antigens examined in all eight species, and 21/21 antigens in the four species of macaques. Detailed immunohistochemistry protocols are presented, along with a systematic approach to developing a protocol for a new antibody.

Activity of interferons alpha, beta, and gamma against human immunodeficiency virus replication in vitro

The antiviral activities of various interferon preparations against human immunodeficiency virus (HIV) were evaluated in vitro. Recombinant interferon alpha-A, and beta interferons and leukocyte-derived alpha interferons show similar concentration-dependent antiviral activity. Recombinant and lymphocyte-derived gamma interferons show minimal antiviral activity against HIV replication in normal peripheral blood mononuclear cells, but definite activity against HIV in the H9 lymphocytic and U937 monocyte-macrophage cell lines.

Experimental inoculation of monkeys with autologous lymphoid cell lines immortalized by and producing human T-cell leukemia virus type-I

Cynomolgus monkeys and squirrel monkeys were inoculated with autologous lymphoid cell lines immortalized by and producing human T-cell leukemia virus type-I (HTLV-I) in order to serve as an animal model of adult T-cell leukemia (ATL). The autologous cell lines were established from peripheral blood mononuclear cells (PBMC) from each monkey by co-cultivation with lethally irradiated MT-2 cells producing HTLV-I. All of these cell lines, which had monkey karyotypes, grew continuously without addition of interleukin-2 (IL-2) and expressed virus-specific proteins of HTLV-I and IL-2 receptor. After inoculation with the autologous cell lines, specific antibodies against HTLV-I proteins could be detected in their plasma, and transformed HTLV-I-infected cells could be recovered from their peripheral blood for at least 6 months. However, no signs of ATL have been observed to data, i.e. 2 years after inoculation.

Depression of lymphocyte responses to mitogens in mangabeys with disseminated experimental leprosy

Mononuclear cells from mangabey monkeys with disseminated experimental leprosy had increasingly severe depression of blastogenic responses to phytohemagglutinin, concanavalin A, and pokeweed mitogen as the disease progressed. Blastogenic responses were not depressed in cells from mangabeys with more localized disease. Blastogenic responses of cells from normal mangabeys appeared to vary with a circannual rhythm. The demonstration of significant negative correlations between the blastogenic responses to mitogens and the percentages of OKT8+ cells suggested that the mangabey OKT8+ subset may contain cells with suppressor function. The depressed responses to mitogens by cells from monkeys with disseminated experimental leprosy were associated with relatively high percentages of OKT8+ cells. Polyclonal immunoglobulin plaque-forming cell responses to pokeweed mitogen were depressed in cells from experimentally infected mangabeys. The results indicated that defects in immune regulation may occur in experimental leprosy in mangabeys, similar in some respects to the defects that have been reported in human leprosy.