Exploration of Immunology

Table 1. Induction of tolerance by the immune and other cells present in human testis

Cells	Special characteristics facilitating tolerance
Macrophages	M2 alternatively activated, production of IL-10
Dendritic cells	Low expression of MHC II, co-stimulatory molecules (CD80, CD86) and CCR7
Suppressor T cells (CD8⁺)	Suppress immune response
Treg cells (CD4⁺/Foxp3⁺)	Inhibit antigen-specific T cell responses
Sertoli cells	Production of immunosuppressive galectin-1, activin A and anti-inflammatory cytokines
Peritubular cells	Production of immunosuppressive activin A and expression of TLR
Leydig cells	Produce MIF and testosterone that have immunosuppressive properties

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TLR: Toll-like receptors; MIF: migration inhibiting factor

Declarations

Author contributions

KK wrote the first draft of the manuscript. DM wrote the section on SARS-CoV-2. DM and SKG made critical changes, edited, and revised the manuscript. All authors approve the final version of the manscript.

Conflicts of interest

The authors declare that they have no conflicts of interest.

Ethical approval

Not applicable.

Consent to participate

Not applicable.

Consent to publication

Not applicable.

Availability of data and materials

Not applicable.

Funding

KK and DM acknowledge Indian Council of Medical Research and Science and Engineering Research Board, Government of India, for funding. SKG acknowledge Indian Council of Medical Research, Government of India for the award of Emeritus Scientist. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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