Two series of experiments were conducted in order to determine the effects of diet on neutrophilic phagocytosis. The first series was designed to determine the effects of varying amounts of oral glucose on phagocytosis. Blood samples from 6 to 8 subjects were drawn at fasting, and at various time periods following ingestion of 12.5, 25, 50, 75, and 100 grams of glucose. In the second series of experiments, blood samples were taken from 11 subjects after an overnight fast and 2 hours following ingestion of one of 4 different liquid diets, which included the following: the meal (I), consisting of protein, fat, and carbohydrate from a starch source; the meal with glucose (II), consisting of protein, fat, and carbohydrate mainly from glucose; 75 grams of glucose only (III); 75 grams of glucose followed 30 minutes later with the meal (I). Following a 30-minute incubation and rotation of all blood samples with bacteria, slides were prepared with Wright’s stain to determine the phagocytic index, the average number of bacteria engulfed per leukocyte.
For the first series of experiments, statistical analysis revealed a significant decrease in phagocytic index 2 hours following ingestion of 100 grams glucose, 3 hours following ingestion of 75 and 100 grams glucose, and 4 hours following the 25, 50, and 75 grams glucose. In the second series of experiments significant decreases in phagocytic index were observed 2 hours 15 minutes following ingestion of the glucose and meal of diet IV, and 4 hours 15 minutes following ingestion of diet III, 75 grams glucose. Although 4 of the tests showed a statistically significant decrease in phagocytic index from fasting, the responses to the various diets and levels of glucose were not significantly different from each other. Also, there were wide variations in phagocytic index from one subject to another. In these experiments, the average fasting phagocytic index was low, possibly not providing an adequate test of phagocytosis.
Additional experiments were run in order to decrease the wide variations in the previously determined phagocytic indices. This was done by increasing the fasting phagocytic index as a result of increasing the bacteria to leukocyte ratio. Although the variations between samples were decreased, there was no significant decrease in phagocytosis 2 hours following ingestion of 100 grams of glucose.
Since previous work (Sanchez et al., 1973; Kijak et al., 1964) has reported a significant decrease in phagocytic index following ingestion of glucose, two approaches were taken. First, the sensitivity of the present technique was tested by using compounds that decrease phagocytosis (EDTA) and increase phagocytosis (CaCl2), using 9 subjects. There was a decreased phagocytic index with the addition of EDTA, although it was not statistically significant with the few subjects involved. The control and the EDTA plus calcium samples showed the same average phagocytic index, as expected. Too few subjects were involved to make a final conclusion concerning the sensitivity of the present technique.
The second approach was an investigation of data from previously reported studies (Sanchez et al.,1973). Several slides from these studies were re-read and were compared with the phagocytic indices previously reported. A significantly lower 2-hour postprandial phagocytic index was reported in the previous study than was observed in the present reading of the same slides. Too few slides were read to make a final conclusion concerning the accuracy of these data.
As it is recognized that variations can occur in bacteria (Browning and Mackie, 1949; Smith, 1969), possibly the Staphylococcus epidermidis used in these experiments differs from that used in previous work, causing the observed difference in response to phagocytosis. However, if the strains are the same, then there is a need for further research into the lack of correlation between the present and previous studies.
Benjamin H. S. Lau
Paul J. McMillan
U. D. Register
Rodney E. Willard
Paul Y. Yahiku
Master of Science (MS)
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Hoover, Linda L., "The Effect of Diet on Neutrophilic Phagocytosis" (1974). Loma Linda University Electronic Theses, Dissertations & Projects. 1470.
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