Retention of "safe" blood donors. The Retrovirus Epidemiology Donor Study

BACKGROUND: There are obvious advantages to increasing donor retention. However, for reasons of blood safety, certain donors may, in fact, be more desirable to retain than others. “Safe” donors are defined as those who provided a blood donation that was negative on all laboratory screening tests and who subsequently reported no behavioral risks in response to an anonymous survey. This study identifies the most important factors affecting the intention of “safe” donors to provide another donation. STUDY DESIGN AND METHODS: An anonymous survey asking about donation history, sexual history, injecting drug use, and recent donation experience was mailed to 50,162 randomly selected allogeneic donors (including directed donors) who gave blood from April through July or from October through December 1993 at one of the five United States blood centers participating in the Retrovirus Epidemiology Donor Study. Before mailing, questionnaires were coded to designate donors with nonreactive laboratory screening tests at their most recent donation. RESULTS: A total of 34,726 donors (69%) responded, with substantially higher response among repeat donors. According to reported intentions only, the vast majority of “safe” donors indicated a high likelihood of donating again within the next 12 months. Only 3.4 percent reported a low likelihood of donating again. A comparison of those likely to return and those unlikely to return reveals significant differences in demographics and in ratings of the donation experience. A higher proportion of those unlikely to return were first-time donors, minority-group donors, and donors with less education. The highest projected loss among “safe” donors was seen for those who gave a fair to poor assessment of their treatment by blood center staff or of their physical well-being during or after donating. CONCLUSION: These data suggest that efforts to improve donors' perceptions of their donation experience, as well as attention to the physical effects of blood donation, may aid in the retention of both repeat and first-time donors.     

Rupture of the posterior tibial tendon: CT and surgical findings

Computed tomography (CT) was performed in 42 patients with 49 clinically suspected tears of the posterior tibial tendon. Twenty-eight of the 49 suspected tears were subsequently surgically explored and repaired. Three patterns of tendon abnormalities were recognized on CT scans: type I-intact, hypertrophied, heterogeneous tendon; type II-attenuated tendon; and type III-absence of a portion of a tendon. Types I and II correlated with partial rupture seen during surgery, and type III correlated with complete rupture of the tendon. CT findings were accurate in 96% of the patients who underwent surgery. In four cases (14%), tendon rupture was seen on CT scans, but the extent of the injury was underestimated and the rupture was misclassified. Reactive periostitis of the distal tibia was seen in 71% of diseased tendons and may represent an important factor in the diagnosis of tendon rupture.     

Platelet satellitism: experimental studies

Platelet satellitism (PS), the in vitro phenomenon of platelets rosetting about nonlymphocytic leukocytes, is an uncommon and poorly understood finding reported in the ethylenediaminetetra-acetic acid (EDTA)-anticoagulated blood of patients with a wide variety of clinical conditions. This report presents experimental studies investigating the nature of this phenomenon by utilizing the blood of patients with platelet satellitism. Wet preparation studies and electron microscopy (transmission and scanning) demonstrated the morphologic sequences involved in the phenomenon, including eventual phagocytosis of platelets by neutrophils. The results of varying conditions such as time, temperature, and anticoagulant are described. All of five patients tested were found to have cryofibrinogenemia. Certain blood components from all of three patients tested were capable of inducing PS in normal whole blood, whereas components from normal subjects usually were not. In one patient (A), the PS-inducing capability appeared to be present in both plasma and platelets. In another patient (B) the PS-inducing capability was present in platelets (in both 1966 and 1975) and also in the cryosupernate of serum and plasma; among various antisera, antifibrinogen had the greatest ability to reduce the degree of PS in patient blood; addition of moderate amounts of CaCl2 and/or MgCl2 did not diminish the phenomenon; and two sisters and two daughters demonstrated no PS. In a third patient (C) the PS-inducing capability appeared to be largely concentrated in the cryoprecipitable fraction of plasma. These studies suggest that there are different factors in the patients' blood resulting in PS. Further studies showed PS could be induced in normal blood by adding certain nonprimate antihuman antisera (anti-IgM, antialbumin or antifibrinogen) and also by adding some preparations of normal washed platelets to the same individuals's normal whole blood. This indicates that the phenomenon of PS can be produced by factors other than those specifically present in patients with PS. Antigen-antibody complexes, either formed in vivo (mixed cryoglobulinemia) or in vitro, did not result in PS when mixed with normal blood. These and other studies suggest that PS can result from the presence of several different factors, usually proteins (in conjunction with EDTA), which probably attach to the surface of platelets apparently resulting in some alteration (such as change in surface charge) causing the platelets to be attracted to and phagocytosed by neutrophils.     

Use of monoclonal antibodies to quantify subclasses of human IgG. II. Enzyme immunoassay to define antigen specific (anti-filarial) IgG subclass antibodies

Because of their single epitope specificity, monoclonal antibodies (Mcabs) may perform with different levels of efficiency in immunoassays depending on the accessibility of the particular epitope recognized. In order to develop assays capable of detecting specific antibodies of each of the four human IgG subclasses, we have evaluated by ELISA the performance characteristics of a panel of Mcabs raised to the subclass proteins. At least one Mcab to each of the four subclasses was identified that was specific in its ability to capture its own relevant IgG subclass without any associated light chain, allotype or isoallotype activity and that was able to function effectively as a probe in an optimized, quantitative ELISA. When IgG subclass antibodies were measured in sera from patients with filariasis using specific filarial antigen, the sensitivities of each subclass antibody assay varied; for IgG1 and IgG4 antibodies the sensitivity of detection was 50 ng/ml and for IgG2 and IgG3, 10 ng/ml. The potency of the Mcab, determined by its titration for use as a probe, did not correlate with the sensitivity of the assay. These Mcabs were also capable of defining IgG subclass antibody responses qualitatively in immunoblot analyses with little or no non-specific binding. The availability of such highly characterized Mcabs for use in quantitative and qualitative definition of specific IgG subclass antibody responses should greatly improve our detection and subsequent understanding of the role of these IgG subclasses in various disease states.