The effect of nutrition on immune response in active pulmonary Tuberculosis

Abstract

INTRODUCTION: Studies identifying the active components of immune response against TB should consider the confounding effects of malnutrition and anaemia, which are known to impair cell-mediated immunity. OBJECTIVES: To compare nutritional status (malnutrition and anaemia) and immune status (lymphocyte subpopulations) of patients with Active Pulmonary Tuberculosis (ATB) with healthy controls 2.To describe the effect of nutritional status on immune response to ATB. METHODS: A cross-sectional, comparative study involving 49 smear-positive TB patients (41 males, median age 35 yrs) and 49 controls (25 males, median age 34yrs) was carried out. Persons with immunosuppress!on (HIV infection, diabetes mellitus, corticosteroid or immunosuppressive therapy) or on nutritional supplementation were excluded. Nutritional status was assessed using anthropometry, haemoglobin and red-cell indices. Labeled monoclonal antibodies against lymphocyte surface markers were used in dual parameter flow-cytometry to quantify (cells/mm3) total T(CD5), T-helper(CD4), T-cytotoxic(CDS), B(CD19), B1(CD19+CD5), Natural-killer(CD56), Natural-Killer-T(CD56+CD3)lymphocytes. Student t-test or Kruskal-wallis test for 2 groups was used where appropriate. p<0.05 was considered significant. RESULTS: Whilst nutritional status assessed by weight (43 vs 57 kg, p<0.001), mid-arm circumference (21.1 vs 27.6 cm, p<0.001) and body mass index (16 vs 20.7 kg/m2, p<0.001) was lower in ATB, anaemia was greater (61.2% vs 12.2%, p<0.001). Means of total lymphocytes (2,475 vs 3,211; p<0.0001) and most lymphocyte subsets (T, CD4, CDS, B and Bl cells) were significantly lower in patients with ATB (n-49) compared to controls (n=49). There was no statistically significant difference in the total lymphocytes, T, CD4, CDS, B, Bl, NK and NKT cells in undernourished TB patients (BMI< 18.5) and anaemic TB patients compared to well-nourished and non-anaemic TB patients. CONCLUSIONS: Malnutrition and anaemia observed in ATB does not have an impact on the peripheral depletion of lymphocyte subsets.