Interleukin-2 secretion by bovine mammary gland mononuclear cells during the nonlactating period.

Bovine blood and mammary gland mononuclear cells were isolated from five primiparous Holstein cows at 14-18 and 28-32 days of involution and 7-13 days prior to parturition and used in a bioassay to determine if bovine mammary mononuclear cells produced interleukin-2 in culture. Interleukin-2 production by mononuclear cells was stimulated in 24 hr cultures using concanavalin A. Bovine interleukin-2 dependent cytotoxic T-lymphocytes were used as target cells. Interleukin-2 production by mammary gland and blood mononuclear cells was comparable. Interleukin-2 production by mammary gland mononuclear cells did not vary significantly over the three time periods evaluated. However, blood mononuclear cells isolated at 28-32 days of involution produced significantly greater amounts of interleukin-2 compared to blood mononuclear cells isolated during the early nonlactating period and the prepartum period. These data suggest that bovine mononuclear cell hyporesponsiveness to mitogens during the nonlactating period is not due to a deficiency in interleukin-2 production.