Regulation of TNF-alpha receptor expression on human neutrophils by various cell activating factors

Since tumor necrosis factor-alpha (TNF-alpha) has been implicated in a wide range of inflammatory states, we sought to examine the regulation of TNF-alpha receptors on human neutrophils (PMNs). We were particularly interested in the relationship of TNF-alpha binding characteristics to various known neutrophil-priming stimuli such as temperature, N-formylmethionyl-leucyl-phenylalanine (fMLP), phorbol myristate acetate (PMA), C5ades Arg, and human recombinant C5a (HrC5a). Competition binding studies indicated that there was no significant change in receptor number or affinity due to the temperature used for neutrophil isolation. PMNs isolated at 4 or 25 degrees C had a single class of receptors with a Kd of 83.1 +/- 3.3 vs 90.0 +/- 8.3 pmole/liter and a similar number of receptors, 1575 +/- 99 vs 1876 +/- 279 receptors/cell. However, when either group of isolated PMNs was further incubated in buffer at 37 degrees C for 15 min, a significant increase in Kd (4-37 degrees C, 147.9 +/- 23.7 pmole/liter; 25-37 degrees C, 165.2 +/- 29.2 pmol/liter) and a decrease in receptor number (4-37 degrees C, 1116 +/- 86 receptors/cell; 25-37 degrees C, 957 +/- 71 receptors/cell) were seen. To determine the effect of other activating substances such as fMLP, PMA, C5ades Arg, HrC5a, 4 degrees C isolated PMNs were used.(ABSTRACT TRUNCATED AT 250 WORDS)