The nucleotide sequence for human IL-4 was isolated four years later confirming its similarity to a mouse protein called B-cell stimulatory factor-1 (BCSF-1).
A secuencia de nucleótidos da IL-4 humana foi illada catro anos despois confirmando a súa semellanza cunha proteína de rato chamada factor-1 estimulador de célula B (BCSF-1).