Increased yields of IgG2a- and IgG3-secreting hybridomas after fusion of B cells from mice with autoimmune diseases.

Hybridoma technology has made the production of antigen-specific monoclonal antibodies feasible and almost routine, but the production of certain biologically desirable antibody isotypes has remained difficult. Three strains of autoimmune mice (MRL/l, NZB, and BXSB) were compared to a normal strain (BALB/c), in fusions with a BALB/c myeloma (NS-1) in order to study the rescue of relevant isotypes with the desired antigenic specificities. Mice from these four strains were immunized with colon carcinoma cells, and the hybridoma supernatants from thirty fusions were analyzed for (1) reactivity with cell surface determinants on the immunizing cell line; and (2) Ig class and subclass isotypes. We found that compared to BALB/c mice, MRL/l mice produced greater numbers, and NZB and BXSB mice comparable numbers, of cell surface-reactive hybridoma clones per fusion. MRL/l mice produced the largest number and highest percentage of cell-surface reactive IgG2a (22.4%) and IgG3 (10.6%) producing clones, followed by NZB mice which produced predominantly IgG2a clones (12.3%). BXSB mice, which have latent autoimmune disease, showed no significant difference from normal BALB/c controls (IgG2a:0.7% and IgG3:1.9% vs. IgG2a:4.8% and IgG3:4.8%). The increase in IgG2a and IgG3 clones derived from MRL/l mice was age-dependent, correlating with the age at which abnormal proliferation of T cell and splenic enlargement occurs (2-4 months). We conclude that MRL/l mice are useful for generating monoclonal antibodies of the IgG2a or IgG3 isotype, provided fusions are performed at the time of maximal lymphoproliferation.