Table 2. The immune suppressive effects of aflatoxin examined in human epidemiological studies.

Study	Location/ study design/ population characteristics	Aflatoxin exposure	Immune markers	Relationship between aflatoxin exposure and child growth impairment
Allen et al72)	- The Gambia - Cross-sectional - 391 children aged 3–8 y*	- AF-alb biomarker (n = 323) - Mean (log) 4.05 pg/mg	- Malaria − Plasmodium falciparum parasitaemia - Antibody titre − asexual stages of P. falciparum - HBV − HBsAg	- Mean AF-alb was significantly higher in children with P. falciparum parasitaemia compared with children no P. falciparum parasitaemia (P = 0.01). - Mean AF-alb levels were higher in children who were HbsAg +ve** than those who were HbsAg –ve**.
Turner et al44)	- The Gambia - Cross-sectional - 472 children aged 6–9 y	- AF-alb biomarker - Detected in 434/466 (93%) - GM (95% CI): 22.3 (20.3, 24.5) pg/mg	- Secretory IgA in saliva (sIgA) - Cell-mediated immunity (CMI) - Antibody responses to both rabies and pneumococcal polysaccharide vaccines	- Children with detectable levels of AF-alb had significantly lower sIgA compared to those with non-detectable AF-alb levels (P < 0.0001). - 1 of the pneumococcal antibody titers was weakly associated with AF-alb (P = 0.05).
Jiang et al45)	- Ghana - Cross-sectional - 64 adults aged 19 to 86 y	- AF-alb biomarker - Mean (SD***) AF-alb: 0.997 (0.40) pmol/mg	- Leukocyte immunophenotypes - Lymphoproliferative response of CD4+ T cells - Cytokine production by CD8+, CD4+ and CD3-CD56+ cells - Monocyte phagocytic function	- Participants with high levels of AF-alb, compared to those with low levels had lower percentages of CD3+CD69+ and CD19+CD69+ cells (P = 0.002), and lower percentages of CD8+ T cells that contained perforin or both perforin and granzyme A (P = 0.012). - AF-alb concentrations were negatively associated with CD3+CD69+ (P = 0.001) and CD19+CD69+ (P = 0.032) cells after adjustment for age and other immune parameters.
Jiang et al46)	- Ghana - Cross sectional - 116 HIV +ve adults: mean age (SD): 38.25 (9.44) y - 80 HIV –ve adults: mean age (SD): 40.77 (17.52) y	- AF-alb biomarker - HIV +ve mean (SD) AF-alb: 1.01 (0.53) pmol/mg - HIV –ve mean (SD) AF-alb: 1.01 (0.41) pmol/mg	- Leukocyte immunophenotypes - Cytokine production by CD8+, and CD3-CD56+ cells - Viral load	- HIV +ve participants with high aflatoxin exposure, had lower CD4+CD25+CD45RO+ regulatory T-cells (P = 0.009) and naïve CD4+CD45RA+CD62L+ T cells (P = 0.029), as well as lower percentages of B-cells (P = 0.03), compared to HIV +ve individuals with low aflatoxin exposure. - Among HIV +ve participants, AF-alb concentrations were inversely associated with perforin-expressing CD8+ T-cells (P = 0.045), T-regulatory cells (P = 0.002) and B-cells (P = 0.012).
Jolly et al74)	- Ghana - Cross-sectional - 155 HIV +ve adults - 159 HIV –ve adults	- AF-alb biomarker - HIV +ve mean (SD) AF-alb: 1.06 (0.60) pmol/mg - HIV –ve mean (SD) AF-alb: 0.91 (0.46) pmol/mg	- Viral load - CD4 count - Liver function parameters - HBV, HCV and malaria infection parameters	- HIV +ve participants with high AF-alb levels(>0.93 pmol/mg albumin based on group median) showed statistically significant increased odds of having higher HIV viral loads (OR, 2.84; 95% CI, 1.17−7.78) and higher direct bilirubin levels (OR, 5.47; 95% CI, 1.03−22.85) compared to the HIV+ group with lower AF-alb levels(<0.93 pmol/mg). - Higher levels of AF-alb were associated with lower levels of albumin (P = 0.01) as well as higher levels of total bilirubin (P = 0.01) and direct bilirubin (P = 0.01) in HIV +ve participants.
Keenan et al75)	- Ghana - Cross-sectional - 141 HIV positive adults	- AF-alb biomarker - Median AF-alb: 0.94  pmol/mg	- CD4+ T- cells - Viral load - Malaria - Tuberculosis - HBV - Pneumonia	- Participants in the highest AF-alb quartile had a higher risk of tuberculosis (HR, 3.39; 95% CI, 1.15−9.98; P = 0.03) compared to those in the lowest quartile.

* y: year; ** +ve: positive, –ve: negative; *** SD: standard deviation