The subcellular localization of beta2-microglobulin (beta 2m) in human neutrophils was determined by an enzyme-linked immunosorbent assay on subcellular fractions obtained by Percoll density gradient centrifugation of neutrophils disrupted by nitrogen cavitation. The neutrophils were found to contain 160 ng beta 2m/mg protein. Approximately two-thirds co-located with the markers for specific granules and was released from intact cells during degranulation, whereas one-third of the beta 2m was

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... cated together with markers of the plasma membrane. This fraction was not further enriched during degranulation. These results indicate that beta 2m cannot be universally used as a plasma membrane marker as hitherto assumed, but beta 2m may serve as an indicator of neutrophil degranulation.