European Journal of Cardiovascular Medicine

Recurrent infections in childhood are common and often reflect repeated exposure to benign pathogens. However, persistent or severe infections may suggest underlying immune dysfunction. The immune system operates via innate and adaptive arms. Adaptive immunity comprises humoral immunity, mediated by B lymphocytes, and cell-mediated immunity (CMI), mediated by T lymphocytes. CMI is crucial in protecting against intracellular pathogens, fungi, and viruses, and its impairment predisposes children to opportunistic infections, poor vaccine responses, and higher morbidity [1,2].

Malnutrition is the leading cause of secondary immunodeficiency in children globally. The World Health Organization estimates that nearly 45 million children under five years suffer from wasting, and 149 million are stunted [3]. In India, the dual burden of infections and malnutrition creates a vicious cycle: infections exacerbate undernutrition, while undernutrition impairs immune competence. Protein-energy malnutrition, in particular, causes thymic atrophy, reduced T-lymphocyte function, and diminished delayed hypersensitivity responses [4,5].

Delayed hypersensitivity testing (DTH) using ubiquitous antigens such as tuberculin, tetanus toxoid, or Candida is a simple in vivo method to assess CMI. In resource-limited settings, the Mantoux test using purified protein derivative (PPD) remains the most feasible. A positive reaction depends on the presence of sensitized T lymphocytes, while anergy indicates defective immunity or severe malnutrition [6,7].

Absolute lymphocyte count (ALC), derived from white blood cell counts, is another accessible marker of immune competence. Lymphocytopenia can reflect nutritional deficiencies, infections, or primary immunodeficiencies. Together, Mantoux reactivity and ALC provide a cost-effective and practical means of screening immune status in children [8].

Few Indian studies have comprehensively assessed the interplay of nutritional status, Mantoux reactivity, and ALC in pediatric populations. With increasing recognition of malnutrition’s role in immunosuppression, such studies are essential to inform interventions. This study was designed to evaluate the influence of clinical and nutritional status on delayed hypersensitivity and ALC in children admitted to a tertiary care hospital, and to analyze Mantoux responses in relation to BCG vaccination. 

A cross-sectional study was conducted at the Department of Pediatrics at Tertiary Care Teaching Hospital over a period of 18 months.

Sample size: 503 children aged 1 month to 18 years were included.

Inclusion criteria:

• Children aged 1 month to 18 years admitted to the pediatric inpatient ward.

Exclusion criteria:

• Critically ill children who could not undergo Mantoux testing.

Methodology:

1. Detailed case history including immunization history of BCG was taken along with general and systemic examination. The observations were noted in a case proforma.

1. Tuberculin skin test was done with PPD-RT 23 with Tween 80 of strength 5TU according to standard technique (Ref of tuberculin test article) with 26-27 gauge needles over volar surface of arm. Indurations were measured twice with transparent scale and were noted in millimeters, once after 48 hours and again after 72 hours. Depending on size of induration,Delayed Hypersensitivity Reaction (DTH) was determined .

Categorized as follows

0-4 mm - Negative DTH

5-9mm – Indeterminate DTH

≥10mm – Positive DTH

1. Weight was recorded in kilograms and height/length in centimeters. In children up to two years of age lengths were recorded with Infantometer whereas in children above two years of age heights were measured with stadiometer. BMI was computed accordingly. The anthropometric data recorded were classified in grades by comparing them with WHO Z scores growth charts. (ref. of WHO)

1. Absolute Lymphocyte count was calculated with formula

ALC(cells/mm3) = WBC (cells/mm3) x percent lymphocytes ÷ 100

Data were Categoried according to The Harriet Lane handbook.. Depending on Age specific Absolute Lymphocyte counts, data is classified into catergerioes Lymphocytopenia,Normal,Lymphocytosis based on age specific normograms.

Statistical analysis:

Data were entered in Microsoft Excel and analyzed using EpiInfo v7.1.5.2 and MedCalc v15.11.4. Continuous variables were summarized as mean ± SD or median (95% CI). Differences were analyzed using Student’s t-test or Mann–Whitney U test. Categorical variables were analyzed using Chi-square or Fisher’s exact test. p-value <0.05 was considered statistically significant

Table 1. Demographic Characteristics

In table 1, Mean age: 81 months (range: 1 month–18.5 years). Male: 53.5%, Female: 46.5%. Rural: 97%, Urban: 3%. Majority from lower socioeconomic status.

Table 2. Nutritional Status

In table 2, Severely underweight: 19%, Underweight: 19%. Severely wasted: 14.6%, Wasted: 13.3%. Severely stunted: 12%, Stunted: 20.5%. Overweight/obese: 2.9%.

Table 3. Mantoux Reactivity vs Nutrition

In table 3, Mantoux positivity higher in well-nourished children. Malnourished children showed significantly reduced positivity (p<0.05).

Table 4. Absolute Lymphocyte Count vs Nutrition

In Table 4 Lymphocytopenia more frequent among malnourished children. Well-nourished children showed significantly higher median ALC.

Table 5. Mantoux Reactivity vs BCG Vaccination

Table 6. Illness Duration and Diagnostic Categories

This study demonstrates a strong association between malnutrition and impaired cell-mediated immunity in children, as evidenced by reduced Mantoux positivity and lower ALC. These findings are consistent with prior studies showing that protein-energy malnutrition causes thymic atrophy, T-lymphocyte deficiency, and diminished delayed hypersensitivity responses[^9,^10].

Similar to our results, Geefhuysen et al. observed in African children that recovery from kwashiorkor was associated with improved skin test reactivity and lymphocyte transformation [11]. Indian studies have also reported a positive correlation between nutritional status and Mantoux response, with undernourished children exhibiting higher rates of anergy [12].

Our findings also confirm that BCG vaccination enhances Mantoux positivity. However, consistent with the Chingleput trial and other long-term studies, the response wanes with age and is influenced by nutritional status [13,14]. This highlights that nutritional rehabilitation is necessary to optimize vaccine-induced immune memory.

The observation that malnourished children were more likely to exhibit lymphocytopenia is supported by studies linking PEM with thymic atrophy and reduced circulating lymphocytes [15,16]. Zinc and micronutrient deficiencies have also been shown to contribute to impaired lymphocyte proliferation and function [17].

This study is one of the few large-scale cross-sectional studies in India assessing both Mantoux and ALC as markers of CMI in children. However, limitations include: use of a single DTH antigen (tuberculin) rather than multiple recall antigens, cross-sectional design limiting causal inference, and reliance on hospital-based population rather than community sample.

Despite these limitations, our findings reinforce the critical importance of addressing malnutrition to enhance immune competence and reduce infection burden in children. Integration of nutritional programs with immunization and infection control strategies is essential.

Malnutrition is strongly associated with impaired cell-mediated immunity in children, demonstrated by reduced Mantoux reactivity and lower lymphocyte counts. Nutritional interventions are vital to improve immune function and reduce morbidity. Strengthening pediatric nutrition and immunization programs in resource-limited settings is a public health priority

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