The immunogenicity and applicability of non-parental antibodies are considerably enhanced by chimeric antibodies. Chimeric technologies are required to create engineered non-IgG antibodies. Consider IgA as an example. The IgA Fc receptor, or FcRI, effectively initiates cytotoxicity. According to reports, a chimeric secretory IgA (SIgA) was created to fight the H5N1 avian influenza by cloning the genes from a mouse mAb against the virus and then fusing them with human IgA constant sections. A number of chimeric human/mouse antibodies, including human IgA1, IgA2, IgG1, IgG2, IgG3, and IgG4, were also effectively created using the heavy chain (VH) and light chain (VL) sequences from a mouse anti-HLA class II hybridoma. The results demonstrated that both IgG1 and both IgA isotypes killed freshly obtained human chronic lymphocytic leukemia cells equally well.