Cost-effectiveness of different MRSA screening methods.

We describe a model to examine the cost-effectiveness of various laboratory-screening approaches to detect methicillin-resistant Staphylococcus aureus (MRSA). A critical literature review was used to derive relevant data on the sensitivity (X), specificity (S) and time to result (T) of different tests. Additional cost information was provided by a hospital. Tests were considered in four interactive groups based on a hierarchy of procedures used in laboratories. X, S and Ts of screening tests were then used in formulae to calculate effectiveness for the various tests. The model was developed to explore the effects on MRSA infection acquisition of differing X, S and T for the different tests in detecting MRSA colonized patients admitted to a high-risk unit such as an intensive care unit. It was concluded that taking a sample from the nose alone and inoculating directly on to Ciprofloxacin Baird-Parker agar without broth incubation and confirmation by a Pastorex Staph-Plus test without any methicillin resistance confirmation test was the most cost-effective approach. The complexity of designing this apparently simple scenario is apparent, and we describe many other factors that would need to be considered to refine this model further. However, this and other models should aid the debate and development of more cost-effective screening strategies given the lack of standardization or agreement concerning so many of the variables within the UK and elsewhere.

Management of nodular goiters and their operative indications.

It remains controversial whether or not nodular goiters should be treated surgically or conservatively. This report reviews our 9-year experience of treating nodular goiters in 334 patients, 44 of whom underwent surgery, and compares the methods of treatment employed from 1990 to 1999 with those employed from 1971 to 1989 when 171 operations were carried out. In accordance with diagnoses made using fine-needle aspiration biopsy (FNAB) and ultrasonography, patients were treated as follows. Those with cysts were given percutaneous ethanol injection therapy (PEIT), and those with solid tumors underwent surgery if cancer of >class 3 was suspected or if the tumors were >3 cm. Consequently, 44 patients with solid tumors underwent surgery and 72 with cysts were treated by PEIT. The number of operations performed annually decreased to half of the pre-1990 figure. During the follow-up of those patients who did not undergo surgery, four with solid tumors and two with cysts later required surgery due to suspected carcinoma of >class 3 in 3 patients or as a result of personal choice in 3 patients. The growth of solid tumors was not able to be measured in most cases. These results indicate that the number of operations performed for nodular goiters can be reduced by PEIT. An accurate cytological diagnosis supports this therapeutic strategy.

Spontaneous antibody-secreting cells in the stomach of gastric cancer patients.

The gastric mucosa has been regarded as an active site of humoral immunity since the discovery of Helicobacter pylori. The present study was conducted to determine the in vivo activity of gastric B cells in 53 gastric cancer patients. B-cell activity was measured by protein-A plaque assay, in which IgA-, IgM-, and IgG-plaque-forming cells (PFC) were counted. The number of PFC was associated with the stage of cancer, but the response of lymphocytes in a non-tumorous area (NML) and tumor-infiltrating lymphocytes (TIL) differed. PFC in both sites were decreased compared to n0 cancer in n1 lymph node metastasis-positive cancer, while only NML showed raised PFC in n2 + (P < 0.05, vs TIL). Cancer cells penetrating the submucosa caused the PFC of TIL (but not of NML) to decrease. Invasion of the intratumor capillary (V) or lymphatic (Ly) vessels also caused PFC to change, showing differences of Ig class; there was a decrease of PFC in V2 (IgG- and IgM-PFC) and in Ly2 (all Ig-PFC). IgA-PFC in Ly1 differed in TIL (decrease of PFC) and NML (increase). PFC also differed in TIL and NML in cancer cells, as follows: TIL < NML in tubular and poorly differentiated adenocarcinoma and TIL > NML in papillary and signet ring cell adenocarcinoma. Changes in lymph node (LNL) and blood lymphocytes were similar to those in gastric PFC whose IgA value was 10 times as much as that of LNL. The 5-year survival rate was significantly better in patients with lower rather than higher PFC such as 89% vs 68%. Gastric B cells thus appear to be active and to reflect gastric mucosal immunity.

An immunohistological study of post-transfusion graft-versus-host disease (GVHD).

We reported clinicopathological, histopathological and immunohistological features of two suggestive cases with post transfusion graft-versus-host disease (GVHD) and examined. In addition, we have declared histopathologic characteristics of acute and chronic GVHD with literatural consideration. On the basis of a review of two cases, we came to the following conclusion; It is implied that early lymphoid proliferation may be useful to make a diagnosis of acute GVHD. Case 2 had pathological confirmation of acute GVHD in the liver and small intestine. In the liver, a damage of interlobular bile ducts and T lymphocytes infiltration close to ducts were the most specific feature of acute GVHD. From an immunohistological study in case 2, it was confirmed that abnormal expression of HLA-DR antigen and the appearance of activated T lymphocytes played an important role in the development of GVHD reaction in the liver.

Improvement of postoperative hypocalcemia by repeated allotransplantation of parathyroid tissue without anti-rejection therapy.

Long lasting postoperative hypocalcemia, an uncomfortable complication of a thyroid operation for hyperthyroidism, was treated with allotransplantation of parathyroid tissue. Small pieces of the parathyroid tissue offered from two unrelated donors were transplanted to an 18-year-old male with severe postoperative hypoparathyroidism. Prednisolone was given for 2 days, but no other immunosuppressive drugs were used. The remaining tissue was stored in frozen for the repeat transplantation. The functional activity of the frozen tissue was determined by the production of parathyroid hormone in the tissue culture medium adjusted to appropriate concentration of calcium. Loss of the graft function, probably due to rejection, was supplemented with repeated grafting. Hypocalcemia was improved by three times of transplantation using frozen tissue (once) and fresh tissue (twice). This preliminary trial demonstrates that the tissue transplantation of the parathyroid gland is effective to lessen the symptoms and medication of postoperative hypoparathyroidism.

Monitoring of B lymphocyte response with the protein-A plaque assay in kidney transplant patients.

The protein-A plaque assay was used for serial monitoring of spontaneous plaque-forming lymphocytes (PFC) in blood or thoracic duct lymph of 30 renal transplant patients. In patients experiencing early or delayed graft rejection, PFC manifested a 10-fold increase over the preoperative or control level within one month of the transplantation. Patients accepting the renal graft did not exhibit a remarkable PFC response. Among the factors examined (proportion of B cells, donor source, acute tubular necrosis, intraoperative blood transfusion, antilymphocyte serum, histocompatibility, and rejection), the PFC response was most closely related to graft rejection. Changes in serum immunoglobulin (Ig) did not appear to correlate with the PFC response. By using Ig-class-specific antisera, secreted Ig was identified as IgG, IgM, and IgA. This may indicate that renal grafts induce polyclonal activation of the recipient's B cells.

Spontaneous antibody-secreting human blood lymphocytes detected with a protein A plaque assay.

Spontaneous antibody-secreting lymphocytes in human peripheral blood were detected and counted by a protein A plaque assay. The level of plaque-forming cells (PFC) in peripheral blood was significantly higher in patients with immune disorders (per 10(6) lymphocytes: IgG PFC, 2,654 +/- 684; IgA PFC, 1,727 +/- 327; IgM PFC, 403 +/- 92) than in normal controls (per 10(6) lymphocytes: IgG PFC, 327 +/- 56; IgA PFC 633 +/- 128; IgM PFC, 215 +/- 105). There was no direct correlation between the PFC numbers of different Ig classes.

Polyclonal antibody secretion induced in human mixed lymphocyte cultures. II. No direct activation of B cells.

Antibody secreting B cells were measured as plaque forming cells (PFC) in a hemolysis-in-gel assay using fluorescein isothiocyanate (FITC) coupled SRBC as targets or protein A coupled SRBC as targets and developing antisera. Peak antibody secretion occurred on day 5 and the highest number of PFC was seen when mitomycin treated stimulator cells: responder cells were used in a ratio of 1:4. The number of PFC in MLC was not correlated to the DNA synthetic response. Antibody secretion in MLC was found to be of IgM, IgG and IgA classes. Significant numbers of PFC in MLC from blood lymphocytes were detected with the protein A technique, but not using FITC-SRBC targets. Compared to spleen cells, fewer PFC were stimulated in blood lymphocytes. B cells alone, enriched by rosetting of T cells, did not respond by antibody secretion or DNA synthesis in MLC. When Lipopolysaccharide (LPS) was added to MLC an additional effect was seen on the number of PFC which may indicate that distinct B cell subpopulations are activated in MLC by LPS.

In vitro characterization of immunological responsiveness of uremic patients.

Uremic patients are thought to have deficient immune reactivity. The mechanisms for immunosuppression are not known. We have studied various in vitro immune response parameters in lymphocytes from uremic patients and from healthy controls. Using polyclonal activating substances, it was found that PHA and LPS responses were reduced in cells from the patient group compared to the control group (p < 0.05). Furthermore, MLC responsiveness using pooled stimulator cells and polyclonal antibody secretion induced by Staphylococcus aureus bacteria in vitro were reduced in the patients (p < 0.05). No differences with regard to proportions of T/B cells in blood were noted between the two groups. No correlation was found between responses of individual cells to different activating substances, with the exception of PHA and ConA. However, low responses to PHA were usually accompanied by a general low responsiveness. Patients were further subdivided into groups according to the type of dialysis treatment, peritoneal dialysis (PD) or hemodialysis (HD), and to the duration of the hemodialysis period (< and > 1 year). Patients treated with PD showed impaired T cell reactivity with loer PHA responses compared to the HD patients (p < 0.05). Between the HD groups there were no significant differences in mitogen or MLC responses. We believe that the differences between PD and HD were due to the facts that the PD patients were older and not in the same nutritional state as the HD patients.

Antibody secretion and DNA synthesis induced by lipopolysaccharide in enriched human lymphocyte subpopulations.

Lipopolysaccharide (LPS)-induced human lymphocyte activation was analysed with regard to DNA synthesis and antibody secretion. Antibody secretion was measured as plaque-forming cells (PFC) against fluorescein isothiocyanate (FITC)-coupled sheep erythrocytes (SRBC) or protein-A-coupled SRBC in the presence of developing antiserum against human IgG, IgA and IgM subclasses. By co-culturing lymphocytes with various concentrations of mitomycin, without impairing cell viability, inhibition of DNA synthesis and antibody secretion by LPS was correlated. Antibody secretion against FITC-SRBC or protein A-SRBC was not stimulated by LPS in B cells enriched by elimination of SRBC rosette-forming cells (E-RFC). In mixtures of enriched T and B cells the number of PFC was much lower than in unseparated lymphocytes, but the highest number of PFC was seen in the enriched E-RFC. However, DNA synthesis by LPS was induced in enriched B cells and not in enriched T cells. The highest DNA synthesis was seen for unseparated lymphocytes. Furthermore, autoradiography studies and experiments in which activated lymphocytes were separated revealed that LPS predominantly stimulated DNA synthesis in non-E-RFC, presumably B cells and only activated a small proportion of E-RFC. Finally, antibody secretion induced by LPS was unchanged following iron treatment but was inhibited by cells adherent to plastic.

Spontaneous plaque-forming human lymphocytes detected with the protein-A plaque assay.

A sizable proportion of fresh human blood and adenoid lymphocytes were found to produce antibodies when tested in the protein-A plaque assay of Gronowicz et al. Plaque formation was not caused by release of passively adsorbed immunoglobulin but depended on active immunoglobulin secretion. We have investigated optimal conditions for plaque formation in this test system. Good reproducibility is obtained only if cells to be tested are kept in the cold before assay, since the antibody-forming capacity of these cells is rapidly exhausted at temperatures above 2 degrees C. In blood lymphocytes the number of IgA-producing cells exceeds those of IgG and IgM, whereas in the adenoid IgG plaque-forming cells dominate. Studies on the use of this method for the monitoring of immune responses are in progress.

Lipopolysaccharide and lipid A-induced human blood lymphocyte activation as detected by a protein A plaque assay.

Various purified cell wall lipopolysaccharides (LPS) from gram-negative bacteria and derivatives of these LPS were tested for their stimulatory capacity for human peripheral blood cells. Immunoglobulin (Ig) production was tested by an indirect plaque-forming cell assay using Staphylococcus aureus protein A-coupled erythrocytes and specific anti-Ig as developing serum. This method allows the detection of the majority of cells secreting Ig of a single class, and the number of plaque-forming cells detected are approximately 100-1000 times the amount obtained using normal sheep red cells as targets. LPS containing the O antigen-specific chain, as well as mutant products only containing lipid A and ketodeoxyoctonate trisaccharide, could induce cell division and antibody synthesis. The polypeptide antibiotic polymyxin B was found to inhibit LPS-induced activation. Furthermore, purified lipid A, complexed with bovine serum albumin, was also found to activate human peripheral blood B cells. These findings demonstrate that human peripheral blood lymphocytes can be activated by LPS and also indicate that lipid A is the active part of these molecules.

Antibody production and DNA synthesis of human lymphocyte subpopulations induced by PPD tuberculin.

Purified protein derivative (PPD) of tuberculin was found to induce antibody secretion and DNA synthesis in human lymphocytes from blood, spleen, tonsil and lymph node. Antibody secretion was measured as plaque-forming cells (PFC) against fluorescein isothiocyanate (FITC) coupled sheep red blood cells (SRBC) in a haemolysis-in-gel assay. Peak antibody secretion by 100 micrograms/ml of PPD was usually seen on day 6 for blood lymphocytes, and varied from day 3 to day 6 for spleen cells. Peak DNA synthesis for blood lymphocytes stimulated by various concentrations of PPD ranged from day 4 to day 7. The highest number of PFC in tonsil and spleen cells was induced by PPD compared to Staphylococcus aureus bacteria Cowan 1, lipopolysaccharide (LPS) and pokeweed mitogen (PWM). Antibody secretion by PPD was not affected when phagocytic cells were removed by iron treatment. PPD stimulated a higher DNA synthesis in unseparated lymphocytes or mixtures of T and B cells than in enriched T or B cell suspensions. PPD did not induce PFC in B cells enriched by the removal of sheep erythrocyte rosette-forming cells (E-RFC). However, more PFC were stimulated by PPD in enriched E-RFC compared to unseparated lymphocytes, which may indicate that most of the FITC-SRBC reactive B cells also form rosettes with SRBC.