Production of the first effective hyperimmune equine serum antivenom against Africanized bees

Victims of massive bee attacks become extremely ill, presenting symptoms ranging from dizziness and headache to acute renal failure and multiple organ failure that can lead to death. Previous attempts to develop specific antivenom to treat these victims have been unsuccessful. We herein report a F(ab)(´)(2)-based antivenom raised in horse as a potential new treatment for victims of multiple bee stings. The final product contains high specific IgG titers and is effective in neutralizing toxic effects, such as hemolysis, cytotoxicity and myotoxicity. The assessment of neutralization was revised and hemolysis, the primary toxic effect of these stings, was fully neutralized in vivo for the first time.

The impact of pretransplant donor-specific antibodies on graft outcome in renal transplantation: a six-year follow-up study

OBJECTIVE

The significance of pretransplant, donor-specific antibodies on long-term patient outcomes is a subject of debate. This study evaluated the impact and the presence or absence of donor-specific antibodies after kidney transplantation on short- and long-term graft outcomes.

METHODS

We analyzed the frequency and dynamics of pretransplant donor-specific antibodies following renal transplantation from a randomized trial that was conducted from 2002 to 2004 and correlated these findings with patient outcomes through 2009. Transplants were performed against a complement-dependent T- and B-negative crossmatch. Pre- and posttransplant sera were available from 94 of the 118 patients (80%). Antibodies were detected using a solid-phase (Luminex®), single-bead assay, and all tests were performed simultaneously.

RESULTS

Sixteen patients exhibited pretransplant donor-specific antibodies, but only 3 of these patients (19%) developed antibody-mediated rejection and 2 of them experienced early graft losses. Excluding these 2 losses, 6 of 14 patients exhibited donor-specific antibodies at the final follow-up exam, whereas 8 of these patients (57%) exhibited complete clearance of the donor-specific antibodies. Five other patients developed ''de novo'' posttransplant donor-specific antibodies. Death-censored graft survival was similar in patients with pretransplant donor-specific and non-donor-specific antibodies after a mean follow-up period of 70 months.

CONCLUSION

Pretransplant donor-specific antibodies with a negative complement-dependent cytotoxicity crossmatch are associated with a risk for the development of antibody-mediated rejection, although survival rates are similar when patients transpose the first months after receiving the graft. Our data also suggest that early posttransplant donor-specific antibody monitoring should increase knowledge of antibody dynamics and their impact on long-term graft outcome.

Proteomic characterization of the multiple forms of the PLAs from the venom of the social wasp Polybia paulista

The phospholipases A(1) (PLA(1) s) from the venom of the social wasp Polybia paulista occur as a mixture of different molecular forms. To characterize the molecular origin of these structural differences, an experimental strategy was planned combining the isolation of the pool of PLAs from the wasp venom with proteomic approaches by using 2-D, MALDI-TOF-TOF MS and classical protocols of protein chemistry, which included N- and C-terminal sequencing. The existence of an intact form of PLA(1) and seven truncated forms was identified, apparently originating from controlled proteolysis of the intact protein; in addition to this, four of these truncated forms also presented carbohydrates attached to their molecules. Some of these forms are immunoreactive to specific-IgE, while others are not. These observations permit to raise the hypothesis that naturally occurring proteolysis of PLA(1) , combined with protein glycosylation may create a series of different molecular forms of these proteins, with different levels of allergenicity. Two forms of PLA(2) s, apparently related to each other, were also identified; however, it was not possible to determine the molecular origin of the differences between both forms, except that one of them was glycosylated. None of these forms were immunoreactive to human specific IgE.

Purification, sequencing and structural characterization of the phospholipase A1 from the venom of the social wasp Polybia paulista (Hymenoptera, Vespidae)

The biochemical and functional characterization of wasp venom toxins is an important prerequisite for the development of new tools both for the therapy of the toxic reactions due to envenomation caused by multiple stinging accidents and also for the diagnosis and therapy of allergic reactions caused by this type of venom. PLA(1) was purified from the venom of the neotropical social wasp Polybia paulista by using molecular exclusion and cation exchange chromatographies; its amino acid sequence was determined by using automated Edman degradation and compared to the sequences of other vespid venom PLA(1)'s. The enzyme exists as a 33,961.40 Da protein, which was identified as a lipase of the GX class, liprotein lipase superfamily, pancreatic lipases (ab20.3) homologous family and RP2 sub-group of phospholipase. P. paulista PLA(1) is 53-82% identical to the phospholipases from wasp species from Northern Hemisphere. The use restrained-based modeling permitted to describe the 3-D structure of the enzyme, revealing that its molecule presents 23% alpha-helix, 28% beta-sheet and 49% coil. The protein structure has the alpha/beta fold common to many lipases; the core consists of a tightly packed beta-sheet constituted of six-stranded parallel and one anti-parallel beta-strand, surrounded by four alpha-helices. P. paulista PLA(1) exhibits direct hemolytic action against washed red blood cells with activity similar to the Cobra cardiotoxin from Naja naja atra. In addition to this, PLA(1) was immunoreactive to specific IgE from the sera of P. paulista-sensitive patients.

Multiparametric analyses of hybridoma growth on glass cylinders in a packed-bed bioreactor system with internal aeration. Serum-supplemented and serum-free media comparison for MAb production

Monoclonal antibodies are one of the most important products of biotechnology and laboratories and companies all over the world are pursuing their large-scale production. Herein we report a protocol for hybridoma cell cultivation over small glass cylinders inside a 3 liter bioreactor vessel which leads to the production and purification--in order of grams--of one MAb intended for human therapeutic use. This protocol proved to be simple, reproducible and cost effective. Three trials are reported: the first two using conventionally serum-supplemented medium culture and producing 3.15 and 2.1 g of purified MAb in 30 and 21 days respectively, and the third one using serum-free medium culture and producing 6 g of purified MAb in 36 days. We have ascertained the stability of the hybridoma by its cloning directly in serum-free medium. The downstream processing of the serum-free trial was done in a single step, concentrating large volumes of supernatant while simultaneously purifying the antibody.

HLA antibody enhancement by double addition of serum: use in platelet donor selection

The identification of HLA class I alloantibodies is important for organ transplantation and platelet transfusion in alloimmunized patients. Because microcytotoxicity testing against frozen trays of lymphocyte panels is rapid and efficient for determining specificities of unknown antibodies, a simple method was devised to increase test sensitivity to weak antibodies. Standard anti-human globulin (AHG)-facilitated microcytotoxicity was modified by the insertion of a double addition-of-serum (DAS) step, and reagent and patient's sera were evaluated by both methods. DAS modification increased antibody titers and, more significantly, made the identification of weak specificities easier because of the twofold to threefold increase in reactivity rates (29-42% for AHG vs. 75-82% for DAS) of panel cells that were expected to be positive, while low (approx. 1%) "extra" reaction rates were maintained for cells that were expected to be negative. DAS was relatively unaffected by variations in serum volumes or target cell preparation, and its use did not significantly increase test time or costs. In a program of platelet donor selection driven by donor antibody rather than donor-recipient antigen matching, DAS greatly facilitated platelet transfusion support for alloimmunized patients.

Human cells allosensitized in vitro release soluble suppressor factors: presence of at least two distinct factors

Human cells allosensitized in vitro release suppressor "factors" (SF) capable of inhibiting a primary mixed lymphocyte reaction (MLR). Preincubation experiments with SF of either responders or stimulators in MLR suggested the presence of at least two distinct suppressor activities: one called SFR, acting on certain responders including the SF producer; the other called SFNR, acting on stimulators in all MLR. These activities can be separated using sorbents composed of monoclonal anti-HLA-DR antibodies on the one hand and mouse or rabbit IgG on the other hand. SFR is found in the effluent and SFNR in the eluate of these sorbents. The SFNR-binding properties are shared by a murine suppressor factor called immunoglobulin-binding factor or IBF. Moreover SFNR, like IBF, is capable of suppressing a secondary in vitro IgG response through the species barrier.