Human neutrophils: evaluation of adherence, chemotaxis and phagocytosis, following interaction with radiolabeled antibodies.

Murine monoclonal antibodies against stage specific embryonic antigen-1 have been found to have high specificity for human neutrophil (PMN) surface receptor, lacto-N-fucopentoase, and is being investigated as an agent for in vivo labeling of PMNs for imaging abscesses. Since specific membrane antigen complexes are vitally important for adherence related PMN functions, PMNs treated with the antibody at various levels of antigenic saturation were evaluated for adherence, chemotaxis and phagocytosis. The adherence and phagocytic activity of the PMNs remained 100% of the control cells at up to 4% and 5% saturation of PMN surface receptors respectively. As the surface receptor saturation increased, the cell function values decreased in a dose dependent fashion. However, the chemotactic ability of the human PMN remained unchanged at any degree of the receptor saturation indicating that either the lacto-N-fucopentoase receptors were not involved in PMN chemotactic function or during incubation, new surface receptors were generated which revived the cell function to its normal state. Since the proposed 100 micrograms antibody dose will saturate only up to 0.4% PMN surface receptors in an adult human, no adverse effect on PMN function is expected.