Evidence is accumulated that ASD is interrelated with certain physiological abnormalities, including oxidative stress and immune dysregulation .
Research suggests the involvement of cytokines in neurodevelopment, beside their effect in some neurological functions, including cognition and memory [18, 27]. Hence, disturbances within cytokine levels may result in multiple neurological outcomes related to ASD .
In addition, disturbance in the levels of oxidative stress may be relevant to the pathophysiology of ASD .
The aim of the present study was to assess the state of immune dysregulation, as estimated from the serum levels of some cytokine (IL-1β, IL-8, TNF-α) and thioredoxin, as an indicator of oxidative stress in children with ASD.
In this work, it was found that 68.6% of autistic patients were males, and male to female ratio was 2.19:1 respectively. This finding is corresponding to previously reported ratios .
Results also revealed that residence in urban areas is not a risk factor of autism. These results are in accordance to the study of . However,  stated that patients with ASD were more common in urban areas.
The current study showed that none of maternal or paternal age was a risk factor for ASD. This was previously proved by . However,  illustrated an association between advancing paternal age and risk of ASD. On the other hand,  showed that high maternal age (> 35 years) may be a predisposing factor for ASD. Moreover,  revealed that the risk of ASD was greater with increase of either paternal or maternal age.
Our ASD patients were anemic as their mean level of hemoglobin was (10.37 ± 1.24 g/dl) compared with (11.55 ± 1.27 g/dl) in healthy children. This finding was in accordance with results of  that revealed an association between ASDS and iron deficiency anemia.
In addition,  reported a frequency of 28.07% of children with ASDs having anemia based on low hemoglobin concentrations; they explained this finding by the high prevalence of diminished iron intake in those children, due to the associated feeding difficulties and food selectivity.
In the present study, the serum levels of IL-1β, IL-8, and TNF-α were significantly higher in patients with ASD in comparison to control subjects (p = < 0.001, 0.04, < 0.001 respectively).
As several pro-inflammatory cytokines are known to be produced by adipose tissue and the serum levels of those cytokines have been correlated with parameters of obesity ; therefore, we measured the weight and height of all the participants and body mass index (BMI) was calculated.
Our results showed no significant difference between the two groups as regard WAZ, HAZ, and BAZ. Thus, it is likely that the elevations in serum levels of those cytokines were significantly associated with the diagnosis of ASD.
In accordance with our results,  indicated that the levels of many immune proteins in plasma, including cytokines, are altered in ASD. Also,  reported high plasma concentrations of pro-inflammatory cytokines, such as IL-1β and IL-8 in autistic patients. The findings of elevated plasma levels of IL-8, a chemoattractant cytokine of important role in inflammation process, coincide to IL-8 elevation reported in the brain and cerebrospinal fluid (CSF) in ASD .
Moreover,  reported higher levels of IL-8 without similar increases in IL-1β or TNF-α. They suggested that IL-8 is the most sensitive pro-inflammatory mediator in autistic.
On the other hand,  found increased TNF-α in the cerebrospinal fluid of autistics.
The disturbed immunity was further evidenced by increased levels of pro-inflammatory cytokines in brain tissue of autistics [11, 25, 42].
In addition, histological changes of microglia cells that were found in different brain areas provide an evidence for activation of the immune system . These histological changes were supported by neuroimaging studies as well as by .
Synaptic dysfunction is consistently thought to be the main underlying mechanism of ASD. Pro-inflammatory mediators, including cytokines, might be involved in different synaptic processes, such as long-term potentiation (LTP), that is involved in synaptic plasticity in learning and memory processes ; cytokines, such as IL-18, IL-1β, and TNF-a, act on many molecular components of LTP in variable fashions .
Our results revealed that none of the analytic serum levels of cytokines were correlated with the severity of autistic symptoms. So it was suggested that the elevation of cytokines observed in this study may represent an abnormal steady-state immune response in subjects with ASD.
Oxidative damage is thought to play a central role in the pathogenesis of autism . Different evidences supported the relation between oxidative stress and ASD. For instance, the evidence of diminished antioxidant capacity besides enhanced production of oxidative stress biomarkers that has been found in children with ASD [48, 49]. Previous reports have shown that the serum thioredoxin level is a good indicator of oxidative stress .
A major concern of this study was to assess the serum level of thioredoxin in children with autism as compared with that of the controls, and it was interesting to find that there was a highly statistically significant increase in the mean serum level of thioredoxin in ASD group as compared with that of the control group (p = 0.001).
These results were in agreement with a study done by  who found that the median serum thioredoxin levels were significantly higher in children with ASD as compared with typically developing children.