Monoclonal antibodies against transferrin. Precipitating mixtures and lack of inter-species cross-reactivity.

The researchers successfully created five stable hybridoma lines using myeloma cells and spleen cells from mice. These hybridoma lines produced antibodies specifically for pig transferrin that showed no cross-reactivity with transferrin from other species like mice, humans, horses, and sheep.

Creation of Hybridoma Lines

• The experiment began with the preparation of five stable hybridoma lines.
• The researchers used two kinds of cells to create these hybridomas: a myeloma cell line known as P3-X63-Ag.653 and spleen cells from mice that received an excessive exposure to pig transferrin—a process known as hyperimmunization.
• The hybridomas, which are essentially fused cells carrying properties of both parent cells, grew well in the mouse peritoneal cavity and produced a certain class of antibodies (IgG1).

Antibody Formation and Testing

• Researchers collected antibodies from the peritoneal cavity, which had accumulated in the ascitic fluids—an accumulation of fluid in the abdominal cavity—over the course of the experiment.
• They tested these antibodies’ ability to induce antigen precipitation, which is a method to confirm the presence of an antigen.
• No precipitation was seen when they tested single antibodies or pairs of antibodies.
• Interestingly, when they experimented with combinations of three antibodies, three out of a possible ten triads showed clear and sharp precipitation zones and rings during immunodiffusion tests carried out in agar gel. This essentially means that the three-antibody combinations were successfully binding with pig transferrin, leading to visible precipitation.

Specificity of Antibodies

• Researchers conducted quantitative enzyme-immunoassays—a type of blood test—to confirm the antibodies’ specificity.
• The results showed that all five antibodies were solely specific for pig transferrin.
• Importantly, they found no cross-reaction (which would imply the antibodies reacting with similar proteins from different species), with transferrins from any of the other species tested: mice, humans, horses, and sheep. This indicates that the antibodies were not only specific, but quite selective, in their interaction.