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Biomedical subjects

J E Kalil

Publications and source records attributed to J E Kalil.

5 recordsLinked to original sources

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.

Animals↗

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.

Animals↗

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.

Antibody Specificity↗