Plasma pyridoxal 5'-phosphate is a significant indicator of immune responses in the mechanically ventilated critically ill.
OBJECTIVE
This study assessed the effect of vitamin B6 status on immune responses in mechanically ventilated, critically ill patients and compared the results with those of healthy controls.


METHODS
This was designed as a cross-sectional observational study. Forty patients in the intensive care unit successfully completed this study. Vitamin B6 intake was recorded for 8 d. Severity of illness (Second Acute Physiology and Chronic Health Evaluation score) was recorded. Thirty-eighty healthy controls were recruited from the physical check unit of Taichung Veterans General Hospital (Taichung, Taiwan). All control subjects were given instruction on how to complete a 24-d diet recall. Vitamin B6 status was assessed by direct measures (plasma pyridoxal 5'-phosphate [PLP] and 4-pyridoxic acid) and indirect measures (erythrocyte alanine and aspartate aminotransferase activity coefficients). Levels of serum albumin, hemoglobin, hematocrit, high-sensitivity C-reactive protein, and immune responses (white blood cell, neutrophil, total lymphocytes, T lymphocytes [CD3], B lymphocytes [CD19], T-helper cells [CD4], and suppressor cells [CD8]) were determined.


RESULTS
Critically ill patients had sufficient vitamin B6 intake but showed marginal PLP deficiency (20.9 +/- 1.5 nmol/L). In addition, critically ill patients had significantly lower and abnormal immune responses than did healthy controls. There was no significant correlation of vitamin B6 intake and erythrocyte alanine and aspartate aminotransaminase activity coefficients with immune indices. Plasma PLP concentration was strongly negatively correlated with high-sensitivity C-reactive protein level. However, plasma PLP was significantly associated with immune responses after adjustment for age, sex, high-sensitivity C-reactive protein, and the other four vitamin B6 indicators.


CONCLUSIONS
Plasma PLP is a significant indicator of immune responses in human subjects. Further research is warranted to study whether vitamin B6 supplementation in critically ill patients improves their immune responses.
School of Nutrition, Chung Shan Medical University, Taichung, Taiwan, Republic of China. ych@csmu.edu.tw
Yi-Chia
YC
Huang
Han-Hsin
HH
Chang
Shih-Chien
SC
Huang
Chien-Hsiung
CH
Cheng
Bor-Jen
BJ
Lee
Su-Ya
SY
Cheng
Kuo-Hsiung
KH
Su
D018806:APACHE; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000410:Alanine Transaminase / Q000378:metabolism; D001219:Aspartate Aminotransferases / Q000378:metabolism; D002097:C-Reactive Protein; D016022:Case-Control Studies; D016638:Critical Illness / Q000628:therapy; D003430:Cross-Sectional Studies; D004912:Erythrocytes / Q000201:enzymology; D005260:Female; D006305:Health Status Indicators; D006760:Hospitalization; D006801:Humans; D008214:Lymphocytes / Q000097:blood; D008297:Male; D011939:Mental Recall; D008875:Middle Aged; D009752:Nutritional Status; D011732:Pyridoxal Phosphate / Q000097:blood* / Q000172:deficiency* / Q000276:immunology; D012121:Respiration, Artificial; D012720:Severity of Illness Index; D025101:Vitamin B 6 / Q000008:administration & dosage* / Q000031:analogs & derivatives; D026681:Vitamin B 6 Deficiency / Q000097:blood / Q000276:immunology*
D011732:Pyridoxal Phosphate; D025101:Vitamin B 6; D002097:C-Reactive Protein; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase