An indirect effect of an antibody on complement deposition and lysis of differently sensitized surrounding cells.

Lysis of papain-treated group A and B erythrocytes by human complement was studied by an anti-A (BRIC. 131) and an anti-B (BRIC. 30) IgM monoclonal antibody in 51Cr release assays. The indirect effect of membrane-bound antibody, i.e. its influence on complement binding to sensitized surrounding cells, was examined in a cold target competition test in which sensitized, non-labelled cells are present along with sensitized labelled cells and complement. The mode by which anti-A antibodies indirectly suppressed lysis of sensitized B cells up to 20-fold was studied by following C1q and C3b binding. C1q binding to both types of erythrocytes was not altered in mixed populations of erythrocytes in the presence of both antibodies. Binding of C3b to a mixture of both cell types was, however, suppressed, when both antibodies were present. C3b deposition in mixed cell populations did not reach a significantly higher extent than deposited to one type of erythrocyte alone. This was consistent with the results from competitive lysis and suggests that the anti-A captured most C3b at high anti-A concentrations and deprived the similarly sensitized B erythrocytes of complement. We think that this phenomenon is not due to an uneven removal of complement regulatory proteins from A and B erythrocytes by papain. Instead, the phenomenon might be due to an inherent property of anti-A mAb to better produce nucleation sites for C3 convertases which, upon binding factor B, better compete for the limiting factor D. A mathematical analysis of cold target competition experiment (containing 2430 individual measurements) also shows that the distribution of complement between the competing A and B erythrocyte population is uneven, since it predicts that in any given antibody combination the majority of complement is bound to A erythrocytes. This is consistent with the measured average percentage of lysis.

Laparoscopic cholecystectomy in a community hospital setting.

Recently, laparoscopic cholecystectomy has become the preferred surgical procedure for removal of the gallbladder. However, many surgeons believe that the safety and efficacy have yet to be proved in the community hospital setting. To address this concern, a retrospective chart review of the initial 271 instances of inpatient laparoscopic cholecystectomy within a community hospital was undertaken. All procedures were performed by 15 general surgeons in private practice and residents in general surgery. Of the 271 patients, 11 were converted to open cholecystectomy. Surgical complications occurred in six of the 260 instances of laparoscopic cholecystectomy (2.3 percent), with only one injury to the common bile duct. Major postoperative complications occurred in 23 patients, including severe postoperative pain (nine patients), prolonged ileus (seven patients), bile leakage (three patients), retained common duct stones (two patients), respiratory failure (one patient) and postoperative myocardial infarction (one patient). The period of hospitalization ranged from one to 64 nights with a median of one night. The operative mortality rate was zero percent. Multivariate analysis identified two factors associated with an increased risk of postoperative complications. Patients 70 years of age or older and patients whose operating times were greater than one hour and 45 minutes were at increased risk for postoperative complications. We believe that these data represent the general outcomes of the laparoscopic procedure in a community hospital setting and lend support to the argument that the procedure can be performed safely and effectively in this setting.