Use of the direct linear plot to estimate, in an immunoglobulin solution, the proportion which is specific monoclonal antibody against an unknown cell surface antigen.

A Cornish-Bowden direct linear plot was used to assess the level of specific monoclonal antibody in a protein A preparation from mouse ascitic fluid. With this method, experimental observations are plotted directly as lines in parameter space and estimates of kinetic parameters are read directly from the plot without need for further calculation. This method is particularly well suited for the analysis of systems, such as the one outlined here, where conventional kinetic analysis is not possible because the preparation contains both specific and non-specific antibody. Results obtained with the direct linear plot showed that estimates of the level of specific immunoglobulin present in a given protein A preparation are consistent, not only within individual experiments, but also throughout a series of experiments using more than one labelled antibody preparation.

Choriocarcinoma xenografts in the nude rat.

The transplantation of a human choriocarcinoma xenograft (CC3) in the nude rat is reported. The tumours grew progressively for up to 5 weeks but subsequently regressed. Our preliminary results suggest that regression of the tumours appears to be dependent on host age.

Preparation and properties of mouse monoclonal antibody (W14A) to human chorionic gonadotropin.

A mouse monoclonal antibody, W14A, has been prepared which reacts with intact human chorionic gonadotropin and its beta-subunit, showing less than 2% cross-reactivity towards the alpha-subunit and 0.5% cross-reactivity towards the beta-subunit of luteinizing hormone. The reagent is suitable for the radioimmunolocalization of choriocarcinoma and trophoblastic teratoma in humans. A preliminary radioimmunoassay has been developed.