Identification of anti-human IgG monoclonal antibodies and monoclonal antibodies with confined subclass reactivity.

In a previous paper, 4 hybridoma cell lines (1B3, 2D5, 2A4 and 2B6) secreting antibodies against heavy chain of human IgG were reported. In this paper a more detailed study of these McAbs was introduced. First of all they were studied with double immunodiffusion test in agarose and it was demonstrated that they were reactive against 3 distinct antigenic determinants of human IgG. This result was also confirmed by ELISA competition test. These McAbs were further analysed for human IgG subclass proteins and it was found that 1B3 McAb gave positive reaction with all subclasses of IgG while the other 3 possessed confined subclass reactivity, i.e. McAb 2A4 did not react with IgG3 (called non-IgG3 McAb), and both McAbs 2D5 and 2B6 did not react with IgG4 (called non-IgG4 McAb). By agarose immunodiffusion test it was shown that: (i) Only transparent precipitation line was formed when McAb reacted with IgG antigen, however, in agarose containing 2% PEG-6000, the transparent precipitation line becomes opaque; (ii) When a mixture of two McAbs against the same antigenic determinants (2D5 and 2B6) was placed into the same well, the precipitation line remained transparent, but if they were not identical (2A4 and 2D5), then opaque precipitation line formed even in the absence of PEG. It was suggested that this phenomenon should be used for preliminary analysis for the identity among McAbs. The confined IgG subclass McAb may be used for the preparation and purification of IgG3 or IgG4 protein before specific McAb against IgG3 or IgG4 is obtained.(ABSTRACT TRUNCATED AT 250 WORDS)