Recent insight into class-specific properties of murine immunoglobulins obtained with the help of monoclonal antibodies.

BALB/c and C57BL/6 mice were immunized with monoclonal anti-DNP IgE, obtained by fusion of PX63AG8-6-5-3 cells with spleen cells from immunized C57BL/6 or BALB/c mice, respectively. With the antiallotype sera thus produced the allotype of IgE (i.e. 7) could be defined since BALB/c is of the Igh-a and C57BL/6 of the Igh-b allotype. The antiallotype 7b does not cross-react with other allotypes. Antiallotype 7a recognizes in addition to allotype 7a also allotypes 7j, 7d, and 7e as expected. Both the complement fixing and the sensitizing activities of murine anti-TNP and anti-DNP monoclonal antibodies were examined. The minimal amount/ml for complement fixation was 0.46 micrograms from one of the IgG1 antibodies, 0.46 from IgG2a, 12.5 ng from IgM, 0.7 micrograms from IgG3. Complement fixation by IgG1 was unexpected. The minimal amount/ml for mouse PCA was 0.5-0.7 micrograms from IgG1, 1.44-2.3 micrograms from IgG2a, 5.6 micrograms from purified IgG2b and about 15 ng from IgE. Sensitization by IgG2a and IgG2b were new findings. Minimal amount/ml for guinea pig PCA was 0.23 micrograms from IgG2a. Minimal amount/ml for rat PCA was 2 ng from IgE.