Calcium metabolism in blood and peritoneal lymphocytes from continuous ambulatory peritoneal dialysis patients.

OBJECTIVE: Cellular immune function in peritoneal dialysis patients has been shown to be depressed, but the mechanism of this immunosuppression has not been ascertained. Because calcium is an important mediator of lymphocyte activation, this study was designed to investigate if there was an alteration of calcium metabolism in the lymphocytes of continuous ambulatory peritoneal dialysis (CAPD) patients. DESIGN: Sixteen CAPD patients were studied at the initiation of CAPD and after two months of treatment. Twenty-three normal controls were also enrolled in the study. Cytoplasmic calcium changes were investigated in response to the mitogen phytohemagglutinin (PHA) in peripheral blood and peritoneal lymphocytes, using the intracellular calcium probe indo-1 and flow cytometry. Baseline cytoplasmic calcium levels and changes in cytoplasmic calcium in response to PHA were assessed at the initiation of CAPD and after two months of therapy. RESULTS: Peripheral lymphocytes of patients and controls had similar calcium baseline levels, but the peritoneal lymphocytes had baseline cytoplasmic calcium levels averaging 81% higher than the corresponding calcium levels of the patients' peripheral blood lymphocytes. As compared to peripheral lymphocytes, the response to PHA stimulation was significantly less in the peritoneal lymphocytes, increasing an average of only 46.8% above baseline. Peripheral blood lymphocytes of the patients responded by an average increase of 78.9% over baseline. Control cells increased an average of 66.3% over baseline. Follow-up studies done two months after the initiation of CAPD indicated there were no significant changes (as compared to month 0) that occurred in baseline or stimulated intracellular calcium concentrations. CONCLUSIONS: While the peripheral lymphocytes of CAPD patients respond adequately to PHA, the high baseline calcium levels of the peritoneal lymphocytes suggest that these cells may be in a state of chronic activation and may respond minimally to an antigenic challenge.

Effect of long-term platelet donation on lymphocyte subsets and plasma protein concentrations.

Previous studies of changes in immune function in platelet donors have investigated subjects who were undergoing plateletpheresis using older equipment that is no longer in general use. Therefore, the purpose of this study was to determine the effect of long-term platelet donation on lymphocyte numbers and subsets and plasma protein concentrations in platelet donors using newer cell separators. Three groups included in the study were nondonor controls (n = 27), long-term whole blood donors (n = 29), and long-term platelet donors (n = 20). Using a cross-sectional analysis, lymphocyte numbers and subsets were determined and compared among the three groups. Plasma concentrations of total protein, globulin, albumin, and IgG were also compared. Among the three groups there were no significant differences in total white blood cell counts, percentage or absolute number of lymphocytes, or percentage or absolute number of lymphocyte subsets. Serum total protein, globulin, albumin, and IgG concentrations of platelet donors were within normal ranges. These data support the current Food and Drug Administration (FDA) and American Association of Blood Banks' standards for the frequency of platelet donation allowed and monitoring required for plateletpheresis donors. Furthermore, these data indicate that the FDA could eliminate the requirement for the warning in informed consents about lymphocyte depletion in platelet donors.

Lymphocyte phenotypes and infection incidence in transfused preterm neonates.

The immunomodulating effects of repeated exposure to blood from multiple donors coupled with an immature immune system may predispose the preterm neonate to an increased incidence of infection in his first few months of life. To test this hypothesis, we compared lymphocyte phenotypes, serum IgG concentrations, and histories of infection and rehospitalization in neonates at 4 months corrected age. Two of the study groups were preterm infants who had been transfused with either frozen, deglycerolized or CMV-negative, gamma-irradiated blood. Control groups consisted of nontransfused term and preterm infants. There were no differences found in lymphocyte phenotypes or serum IgG concentrations of controls or transfused infants. No differences were found in the infection or rehospitalization incidence in the transfused infants as compared with nontransfused preterm neonates. We failed to show differences in immune parameters or in infection and rehospitalization rates of the preterm infants analysed. Alongside previously published reports, our data suggest that red cell transfusions have a minimal impact on the immature immune system of the neonate.

Plasma proteins and lymphocyte phenotypes in long-term plasma donors.

BACKGROUND: The possible effects of long-term plasma donation remain unknown, but it is important to investigate them so that donor safety is ensured. The purpose of this study was to determine if long-term plasma donation alters plasma proteins or lymphocyte phenotypes. STUDY DESIGN AND METHODS: Two groups of long-term plasma donors, source plasma donors (n = 20) and Rh immune globulin plasma donors (n = 26), were compared with whole blood donors (n = 29) and nondonor controls (n = 30). Blood samples were obtained prior to donation. Serum protein, albumin, globulin, and immunoglobulin levels were determined. In an assay using whole blood, lymphocyte phenotypes were characterized with a panel of single- and dual-labeled monoclonal antibodies and subsequent analysis by flow cytometry. RESULTS: As compared to the nondonor controls and/or whole blood donors, the mean values for serum protein, globulin, and IgG levels were lower in both plasma donor groups, with a significant negative correlation between donation frequency and serum protein values for the source plasma donors. Albumin levels were within normal ranges for both groups of plasma donors. No significant differences existed among the donor groups in total white cell counts, the percentage or absolute number of lymphocytes, T (CD3) cells, or helper T (CD4) cells. However, there were increased percentages of B (CD19) cells and decreased percentages of suppressor T (CD8+/CD11b+) cells and natural killer cells in both groups of plasma donors as compared to nondonor controls. CONCLUSION: Many plasma donors have low levels of serum protein, globulin, and IgG. In addition, they have increased percentages of B cells and decreased percentages of suppressor T and natural killer cells. The clinical significance of these findings warrants further investigation.

Lymphocyte phenotypes in infants are altered by separation of blood on density gradients.

Flow cytometry techniques for immunophenotyping have revolutionised the diagnosis and monitoring of paediatric immunological disorders. Although recent studies in adult subjects discourage the use of density gradients for cell preparation prior to phenotyping, these procedures continue to be used. The purpose of this study was to determine the effect of density gradient separation on lymphocyte phenotypes from neonates, infants, and adults as compared to whole blood determinations. Subset distributions were different with the two procedures. In all three groups, CD19+ (B cell) and CD8+ (suppressor/cytotoxic T cell) percentages were significantly lower and CD3-CD56+ (NK cell) percentages were significantly higher in the density gradient separated cells. The loss of CD8+ cells in density gradient separation was shown to be a selective event. The CD8+CD11b- (cytotoxic T) subset percentages were lower in the density gradient separated cells, while the percentages of CD8+CD11b+ (suppressor T) cells were not affected by separation procedure. Because of the selective loss of lymphocytes on density gradients, the use of a whole blood technique for immunophenotyping in paediatric subjects is recommended.

Characteristics of peripheral and peritoneal lymphocytes from continuous ambulatory peritoneal dialysis patients.

The role of peritoneal lymphocytes in host immunity for continuous ambulatory peritoneal dialysis (CAPD) patients is just beginning to be understood. CAPD therapy increases the proportion of peritoneal lymphocytes, most of which demonstrate signs of activation. There are decreased peritoneal T cells and increased peritoneal B cells as compared to the patients' peripheral blood. When studies examine immunophenotypes of peripheral and peritoneal lymphocytes over time, no significant changes are found. Although changes in peritoneal lymphocyte subsets occur during peritonitis episodes, there are no changes in peripheral blood lymphocytes. The purpose of this article is to provide a brief review of research that has studied lymphocytes in CAPD patients.

Investigation of the effect of long-term whole blood donation on immunologic parameters.

Few studies addressing possible immune sequelae of long-term whole blood donation have been published. The purpose of this study was to determine if there were any differences in lymphocyte subsets, monocyte and neutrophil receptors, and antigens important to host defense in committed whole blood donors and in nondonor controls. Blood samples were obtained from 27 whole blood donors who had been donating on a regular basis for at least 4 years and from 21 nondonor controls. A panel of single- and dual-labeled monoclonal antibodies was used to characterize peripheral white cells, and then the cells were analyzed by flow cytometry. Lymphocyte subsets included T (CD3) cells, helper T (CD4) cells, suppressor T (CD8) cells, B (CD19) cells, natural killer (NK) (CD56) cells, and subpopulations of T cells defined by the coexpression of markers for CD3/HLA-DR, CD3/CD56, and CD8/CD11b. Monocyte and neutrophil analysis included quantitation of receptors for C5a, formyl-met-leu-phe, and C3bi (CR3). Monocytes were also analyzed for expression of HLA-DR and CD14 antigens. No significant differences were observed in the whole blood donors and nondonor controls for any of these factors used to assess immunologic status, except for an increase in C3bi receptors on both neutrophils and monocytes from whole blood donors. These findings indicate that the lymphocyte parameters analyzed in this study are unaltered by long-term whole blood donation. Further research is necessary to determine the significance of complement receptor upregulation in whole blood donors and to identify any changes in the functional characteristics of peripheral white cells from whole blood donors.

In vitro effects of cetirizine and histamine on human neutrophil function.

IgE-mediated hypersensitivity reactions are characterized by an immediate or early-phase response within the first 30 minutes of exposure to allergen, followed by a late-phase response that begins two to six hours later. Histamine is released during both the early- and late-phase responses and inhibits a variety of neutrophil functions, including superoxide anion generation, chemotaxis, and enzyme secretion. There is some debate as to whether histamine's action on neutrophils is mediated through H1 or H2 receptors, or through a single receptor that recognizes both H1 and H2 agonists. In an effort to understand the mechanism of action of the H1-antagonist cetirizine, we studied its effects on a variety of neutrophil functions. We found that at concentrations up to 35 micrograms/mL), it does not affect superoxide anion production or degranulation. However, at higher concentrations (greater than 35 micrograms/mL), a concentration-dependent inhibition of superoxide anion production is observed. This inhibition is most apparent with responses stimulated by chemotactic factors. Limited inhibition of degranulation and chemotaxis is also seen at high concentrations, but at a level far below that seen with superoxide anion production. These studies indicate that neutrophil function is not altered by the circulating concentrations of cetirizine attained during therapy (less than 10 micrograms/mL), but may be suppressed at higher concentrations. Additional effects of cetirizine on neutrophil function, possible influences of the drug on the inflammatory response, and histamine's modulation of neutrophil function are discussed.