Synthesis of a gene encoding bovine substance P precursors and its expression in Escherichia coli

Effect of substance P and its precursor alpha-protachykinin on intracellular free calcium concentration in human polymorphonuclear leukocytes

The increase in intracellular free calcium concentration is an important step in signal transduction leading to phagocyte activation. The undecapeptide substance P can influence various functions of human polymorphonuclear leukocytes, including chemotaxis, phagocytosis, and respiratory burst. In this study we investigated the ability of low-concentration (that can occur in vivo) substance P (10(-7) M) and its precursor alpha-protachykinin (3 x 10(-7) M) to increase the intracellular free calcium concentration in human polymorphonuclear leukocytes. Cells isolated from ten healthy donors were incubated with substance P or alpha-protachykinin in 1 mM calcium medium for 5 min and the intracellular free calcium concentration was monitored using the fluorescent calcium indicator Fura-2am. Polymorphonuclear leukocytes from 40% of donors responded to both agonists. The substance P- and alpha-protachykinin-induced increase in intracellular free calcium concentration was 59 +/- 13 nM and 58 +/- 12 nM and the extracellular calcium influx contributed to 87 +/- 8% and 54 +/- 8% of the calcium response, respectively. alpha-Protachykinin released almost all the calcium from intracellular stores, while substance P mobilized only 24 +/- 5% of this calcium pool. Finally, cells that responded to a single challenge with substance P and alpha-protachykinin were able to increase their intracellular free calcium concentration in response to each of three consecutive stimulations with these agonists. This may be an additional mechanism by which substance P and its precursor modify the function of human polymorphonuclear leukocytes.

Modulation of antigen-presenting capacity of human monocytes by HIV-1 GP120 molecule fragments

The two fragments of HIV-1 gp120 molecule were synthesized to study their interaction with human monocytes. Previous observations indicated that recombinant gp120 fragment (aa residues 410-511) encompassing CD4 binding region (rp120cd) induced tumour necrosis factor alpha (TNF) production in monocytes, while a similar fragment (rp120) not containing the CD4 binding sequence (aa 446-511) was inactive. This paper shows that rp120cd depressed monocyte ability to present antigen (PPD) to autologous T lymphocytes while rp120 was noninhibitory. The rp120cd interacted with monocytes but not T lymphocytes. Anti-TNF receptor type A antibody (utr-1) prevented the depression of antigen presentation caused by rp120cd, which suggested a role for TNF and its receptor. The depression of antigen presentation was seen only when monocytes were treated with rp120cd before, but not after, pulse with antigen. Parallel changes were observed in PPD-induced IL-6 production. Thus, induction of TNF by gp120 may be associated with impairment of antigen-presenting capacity of monocytes seen in AIDS patients.