Any process that stops, prevents, or reduces the rate of B-1 B cell differentiation.
Comment:
Note that immunologists typically use the word 'development' to refer to cells of B or T cell lineages undergoing the process that GO describes as 'cell differentiation'.
Synonyms:
exact_synonym:
down regulation of B-1 B cell differentiation; downregulation of B-1 B cell differentiation; negative regulation of B-1 B lymphocyte differentiation