N-Terminal Ten Amino Acid Sequence Determined for B-Cell Differentiation Factor Derived from Rabbit Breast Milk Cell Supernatant

The rabbit has provided a useful model for the study of mucosal immunity (1). Indeed, the bulk of the rabbit immune system lies within the gut associated lymphoid tissue. At birth, these tissues are poorly developed; however, shortly after birth, these gut associated lymphoid tissues enlarge and become capable of mounting an immune response (2). Temporally, these changes occur during breast feeding. Breast milk contains a variety of cellular elements, including T cells and B cells, as well as a predominance of macrophages, all capable of responding to polyclonal activation and antigen (3). This study defines the N-terminal 1–10 AA sequence for a naturally occurring B-cell differentiation factor arising from rabbit breast milk cells.