Table 2 Summary of specific observations of As-associated immune-related effects

↓ nTreg lymphocyte number & function in adults; redistribution in rat model of autoimmune disease

nTreg cells play critical role in immune homeostasis; alterations could affect self-recognition or influence autoimmune disease

[30]

Prenatal As exposure ↓ infant thymic size & function

Thymus is site of T-cell development; impaired function may account for ↑ prevalence of As-associated respiratory, cancer & other immune-related effects in adulthood

[77, 80]

↓ CD4/CD8 T-cell ratio in children & mice

Indicator of immune suppression

[67, 92]

↓ Rejection of MHC mismatched heart/bone marrow allografts in mice

↓ Immune surveillance could lead to immunocompromised state & ↓ ability to fight infection/cancer cells

[107, 108]

↓ Resistance in mice against B16F10 melanoma resulted in 7-fold ↑ tumor burden

↓ Anti-tumor immunity could lead to cancer development

[94]

↓ Migration of lymphocytes, macrophages & neutrophils to lungs/DC to lymph nodes early in course of H1N1 influenza infection in mice

↓ Immune surveillance could lead to immunocompromised state & ↓ ability to fight infection/cancer cells

[110]

↓ DC density, IL-17 & Th17 cells in asthmatic mouse airways; ↓ Th17 cell differentiation & IL-17 release via disrupted JNK/c-Jun pathway & DC function

Th17 cells play a major role in defense against infection via release of major pro-inflammatory cytokine IL-17; disruption could ↓ ability to fight infection

[111, 112, 120, 121]

↓ Urinary HBD1 peptides in men; ↓ DEFB1 mRNA in human 293 T renal and HeLa cervical cells

HBD1 is antimicrobial peptide implicated in host anti-tumor & pulmonary immunity; its down-regulation could contribute to As-induced cancers & respiratory illnesses observed in humans

[50]