Revisiting Castlio and Ferris-Swift's experiments testing the effects of splenic pump in normal individuals

Background: Castlio and Ferris-Swift conducted a series of experiments in the 1930s testing the scientific basis for using splenic pump manipulation to stimulate the immune system. Their work is still cited as evidence that the splenic pump technique is beneficial. However, they only reported case summaries of the data, indicating what percent of the cases increased or decreased relative to baseline and, therefore, limiting the certainty of their conclusions. To our knowledge, no one has published research confirming their findings. Objective: Our hypothesis is that an updated analysis of the raw data will support the original conclusions that splenic pump manipulation does increase leukocyte counts, lower the erythrocyte counts, not change the leukocyte differentials, and increase the opsonic index. Methods: Wilcoxon signed rank tests were used to determine whether there was a significant change in blood cell counts, leukocyte percent differentials, and the opsonic index following splenic pump manipulation. Using Mann-Whitney U-tests, the change from baseline in leukocyte and erythrocyte counts for the first 23 cases managed by an honorary fraternity were compared to the cases managed by Castlio and Ferris-Swift. P values ≤0.05 were considered significant. Results: Consistent with Castlio and Ferris-Swift's original conclusions, there was a statistically significant rise in the mean leukocyte counts, a decrease in the mean erythrocyte counts, no change in the leukocyte differentials, and an increase in the opsonic index following splenic pump treatment. However, subgroup analysis shows that most of the mean increase in the leukocyte count came from the first 23 subjects processed by a fraternity. The erythrocyte counts were less affected by this variable while the differential and opsonic index tests were unaffected because Castlio and Ferris-Swift performed these. Discussion: Statistical analysis of Castlio and Ferris-Swift's published raw data lends support to their original conclusions. However, subgroup analysis showed a distinct difference, relative to the rise in serum leukocytes, between subjects managed by the fraternity and those managed by the Castlio and Ferris-Swift research team. Conclusion: Modern, well-designed studies which incorporate demographic information, blinding methods to limit measurement bias, and a control group are needed to clarify the effect of the splenic pump on blood cell counts and other immune parameters.