Functional CD47/signal regulatory protein alpha (SIRP(alpha)) interaction is required for optimal human T- and natural killer- (NK) cell homeostasis in vivo - PubMed (original) (raw)

. 2011 Aug 9;108(32):13224-9.

doi: 10.1073/pnas.1101398108. Epub 2011 Jul 25.

Nicholas D Huntington, Maho Nagasawa, Arjen Q Bakker, Remko Schotte, Hélène Strick-Marchand, Sandra J de Geus, Stephan M Pouw, Martino Böhne, Arie Voordouw, Kees Weijer, James P Di Santo, Hergen Spits

Affiliations

Functional CD47/signal regulatory protein alpha (SIRP(alpha)) interaction is required for optimal human T- and natural killer- (NK) cell homeostasis in vivo

Nicolas Legrand et al. Proc Natl Acad Sci U S A. 2011.

Abstract

The homeostatic control mechanisms regulating human leukocyte numbers are poorly understood. Here, we assessed the role of phagocytes in this process using human immune system (HIS) BALB/c Rag2(-/-)IL-2Rγc(-/-) mice in which human leukocytes are generated from transplanted hematopoietic progenitor cells. Interactions between signal regulatory protein alpha (SIRPα; expressed on phagocytes) and CD47 (expressed on hematopoietic cells) negatively regulate phagocyte activity of macrophages and other phagocytic cells. We previously showed that B cells develop and survive robustly in HIS mice, whereas T and natural killer (NK) cells survive poorly. Because human CD47 does not interact with BALB/c mouse SIRPα, we introduced functional CD47/SIRPα interactions in HIS mice by transducing mouse CD47 into human progenitor cells. Here, we show that this procedure resulted in a dramatic and selective improvement of progenitor cell engraftment and human T- and NK-cell homeostasis in HIS mouse peripheral lymphoid organs. The amount of engrafted human B cells also increased but much less than that of T and NK cells, and total plasma IgM and IgG concentrations increased 68- and 35-fold, respectively. Whereas T cells exhibit an activated/memory phenotype in the absence of functional CD47/SIRPα interactions, human T cells accumulated as CD4(+) or CD8(+) single-positive, naive, resting T cells in the presence of functional CD47/SIRPα interactions. Thus, in addition to signals mediated by T cell receptor (TCR)/MHC and/or IL/IL receptor interactions, sensing of cell surface CD47 expression by phagocyte SIRPα is a critical determinant of T- and NK-cell homeostasis under steady-state conditions in vivo.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1.

Fig. 1.

Human cell engraftment in BALB-HIS mice using mCD47-expressing hHPC. Human cell engraftment in 12-wk-old control (n = 9) and mCD47/BALB-HIS mice (n = 10). (A) Frequency and (B) total number of human cells harvested from BALB-HIS mice generated either with control- or mCD47-transduced hHPC (horizontal bar is the mean value). (C) Number of hCD45+ cells generated in vivo from a normalized amount (10,000) of GFP− or GFP+ hHPC (mean + SEM). When statistically significant, the increase in cell numbers observed in mCD47/BALB-HIS mice is indicated (fold increase over control). BM, bone marrow.

Fig. 2.

Fig. 2.

Kinetic of hHPC niche reconstitution in mCD47/BALB-HIS mice. (A) Frequency of CD34+CD38− hHPC among human GFP+ cells harvested in the bone marrow of 12-wk-old control (n = 9) and mCD47/BALB-HIS (n = 10) mice. (B) Normalized number of CD34+CD38− hHPC recovered at week 1 (liver; n = 5 control vs. n = 5 mCD47), week 4 (bone marrow; n = 8 control vs. n = 7 mCD47), and week 12 (bone marrow; n = 9 control vs. n = 10 mCD47) posttransplantation.

Fig. 3.

Fig. 3.

Accumulation of mCD47-expressing T, B, and NK cells in the spleen. Human T-, B-, and NK-cell subsets in the spleen of control (n = 8) and mCD47/BALB-HIS mice (n = 10). (A) Representative CD3 and CD19 expression on hCD45+ GFP+ splenocytes harvested from 12-wk-old mice. Graphs show frequency of T cells (CD3+) and B- to T-cell ratio among GFP+ human splenocytes. (B) Normalized number of human T and B cells (from 10,000 hHPC). (C) Histological analysis of the spleen for the presence of human hematopoietic cells (hCD45), T (hCD3), and B cells (hCD20). H/E, H&E. Pictures were obtained in successive sections from one representative animal from each group. (D) Representative CD16 and CD56 expression among hCD45+GFP+CD3− splenocytes and NKp46 expression among GFP+CD16hiCD56lo NK cells. The graph shows the frequency of total NK cells (pooled CD16−CD56+NKp46+ and CD16hiCD56loNKp46+) among hCD45+GFP+ cells. (E) Normalized number of human total NK cells (from 10,000 hHPC).

Fig. 4.

Fig. 4.

Phenotype and survival capacity of mCD47-expressing T cells. (A) Proportion of CD4+, CD8+, and DP cells among GFP+ spleen T cells in 12-wk-old control (n = 9) or mCD47/BALB-HIS (n = 10) mice. (B) Normalized numbers of CD4+, CD8+, and DP T cells (from 10,000 hHPC). (C) Proportion of TN, TCM, and TEM cells in the CD4+, CD8+, and DP GFP+ T cells. (D) Isotype control and Ki67 staining on splenocytes from one representative mouse from each group. The percentage of Ki67+ T cells is given. The numerical analysis is shown in the graph (n = 5 per group). (E) Plasma concentration of total human IgM and IgG in 12-wk-old control (n = 9) vs. mCD47/BALB-HIS (n = 27) mice (IgM: 1.1 ± 0.4 vs. 77.8 ± 25.6 μg/mL; IgG: 15.3 ± 7.9 vs. 529.1 ± 112.6 μg/mL). (F) Adoptive transfer of control or mCD47/BALB-HIS spleen T cells into adult, nonmanipulated BALB/c Rag2−/−IL-2Rγc−/− mice. The number of human GFP+ T cells recovered from the spleen of the recipient mice is plotted as a percentage of recovery from the initial inoculum (n = 4 control vs. n = 3 mCD47 per time point).

Fig. 5.

Fig. 5.

Human cell reconstitution in BALB/c NOD.sirpa Rag2−/−IL-2Rγc−/− mice. Human cell repopulation in control (n = 6) and NOD._sirpa_-HIS mice (n = 5) 12 wk after hHPC injection. (A) Total number of human cells in the bone marrow, thymus, and spleen. (B) T-cell frequency, total T-cell number, and B- to T-cell ratio in the spleen. (C) Relative proportion of TN, TCM, and TEM cells within spleen CD4+ and CD8+ T cells. (D) Number of human NK cells (NKp46+) in the spleen.

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