A New Sensitive and Specific Bioassay for Lactogenic Hormones: Measurement of Prolactin and Growth Hormone in Human Serum*

Abstract

The replication of Nb 2 Node rat lymphoma cells in suspension culture is specifically stimulated by lactogenic hormones. Human (hPRL), ovine, bovine, and rat PRLs stimulated replication in a dose-dependent manner in the concentration range of 10 pg/ml to 1 ng/ml. Human, ovine, and bovine placental lactogens were similarly active. In addition, cell replication was stimulated by human GH (hGH), which is known to have lactogenic activity. Other hormones and growth factors examined were inactive. The growth stimulatory effects of hPRL and hGH were completely inhibited when excess anti-hPRL and anti-hGH, respectively, were added to the medium. A bioassay based on the response of the Nb 2 Node lymphoma cells to lactogenic hormones has been developed. Human serum stimulated cell replication. The effect was completely abolished if excess antibodies to both hPRL and hGH were present. The stimulation obtained with a number of human serum samples correlated very well with the sum of the hPRL and hGH concentrations in the sera, as determined by RIA (r = 0.95; P < 0.001). The concentrations of either hPRL or hGH in human serum could be individually determined by specifically blocking the growth stimulatory effect of the other hormone by adding excess anti-hGH or anti-hPRl. The sensitivity of this bioassay for PRL and hGH in serum exceeds that of RIAs.

Activity of human growth hormone and related polypeptides on the adipose conversion of 3T3 cells.

“…Growth hormone produces effects in several culture systems (3, 11-13, 22, 30), but not with enough sensitivity and specificity to permit those systems to be used as an assay, except for primate growth hormone, whose prolactin activity can be assayed by using a prolactin-dependent cell line (35). It has recently been shown that growth hormone of several species promotes the adipose conversion of preadipose 3T3 mouse cells (23).…”

A possible role of prolactin in adjuvant arthritis

“…The mechanism of action of prolactin on immune reactions is still obscure. The dependence of the Nb2 rat lymphoma on prolactin for its growth (22,23,25) suggests that this pituitary hormone may act directly on lymphocytes as a growth factor. However, indirect effects through organs that play key roles in immunity, such as the thymus or spleen, cannot yet be excluded.…”

Genetic Engineering and Biotechnology of Growth Hormones

“…The biological activity of hormones produced in Pichia pastoris recombinant was determined by their ability to promote proliferation of the Nb2 cell line, which comes from rat lymphoma (54,55). GHs were also tested for their somatogenic activity in the adipocyte differentiation model based on the glyceraldehyde 3-phosphate dehydrogenase (GPDH) assay.…”