Plasma containing HNA-3a antibodies can serve as the second event in a two-event, in vitro model of PMN-mediated pulmonary endothelial damage. The number of viable HMVECs/mm2 (mean ± SEM) as a function of the second event: media-treated controls (left), fresh plasma (FP)–treated HMVECs (middle), and plasma with HNA-3a antibodies (right). HMVECs incubated with media, LPS, PMNs, or LPS + PMNs as the first events were unaffected by media (control, left group) or FP (middle group). However, PMN-mediated damage occurred only with LPS activation, the addition of HNA-3a+ PMNs, and incubation with 5% plasma containing antibodies to HNA-3a. Importantly, Fc blockade, by preincubation with (Fab′)2 fragments from murine monoclonal antibodies against human CD16, CD32, and CD64 did not affect HNA-3a antibody-induced PMN-mediated damage of LPS-activated HMVECs nor did Fc blockade affect the number of viable HMVECs activated with LPS and incubated with PMNs + FP. *P < .05 compared with all other treatment groups.
