Vidar Lehmann

Negative selection of human monocytes using magnetic particles covered by anti-lymphocyte antibodies

We have developed a standardized procedure for the isolation of monocytes from peripheral blood by negative selection using magnetic polymer particles coated with monoclonal antibodies against T and B lymphocytes. The average purity of the monocyte suspension was 85%, and monocyte recovery was 72% from Ficoll-Hypaque gradient separated mononuclear cells and 32% from whole blood. In a lucigenin enhanced chemiluminescence assay there was no significant difference between cells separated immunomagnetically and those separated on a gradient. Nor did electron microscopy show any significant difference in morphology between such monocytes. Negative selection using magnetic polymer particles is an efficient method for the separation of monocytes with intact morphology and function as measured by chemiluminescence.

Direct determination of lithium in serum by atomic absorption spectroscopy.

A direct method for the determination of lithium in serum by atomic absorption spectroscopy is described, employing 0.1 N hydrochloric acid as a diluent. The method is simple and sufficiently reliable for clinical purposes.

Monocyte phagocytosis of opsonized Neisseria meningitidis serogroup B

The chemiluminescence (CL) was examined when peripheral blood monocytes were incubated with opsonized Neisseria meningitidis, serogroup B, serotype 15:P1.16 or serotype 2a:P1.2. The monocytes were separated from a mononuclear cell suspension by an immunomagnetic negative selection technique using magnetic polystyrene microspheres coated with monoclonal antibodies specific for T and B lymphocytes. More than 90% of the lymphocytes were removed, yielding a suspension containing 93% monocytes. Optimal sensitivity for phagocytosis was obtained using 1% serum (10 μl), 72 bacteria per monocyte cell, and 7.5 min opsonization and incubation time during continuous agitation at 37°C. The CL was amplified by lucigenin. Preliminary experiments suggest that convalescent sera from patients with group B meningococcal disease induced increased CL responses compared to acute sera. Sera from volunteers immunized with an outer membrane complex vaccine from serogroup B, serotype 15:P1.16 or 2a:P1.2 meningococci also induced increased CL activity compared to preimmune sera. No such response was shown when a group B capsular polysaccharide vaccine was given. This response pattern was also demonstrated by a flow cytometric phagocytosis technique (FCM). Internalization of meningococci by monocytes was demonstrated by a FCM quenching technique and by transmission electron microscopy. CL and FCM represent rapid and reproducible methods for the measurement of opsonophagocytosis of meningococci by monocytes and may be performed with minute amounts of sera.

United Nations peacekeeping: Medical personnel and international humanitarian law

This paper raises the question whether the Geneva Conventions and Protocols describe in a sufficiently clear and complete manner the obligations and rights of United Nations (UN) peacekeeping forces, with emphasis on the medical services. After reviewing the formal position of International Humanitarian Law (IHL) in former and current UN peacekeeping missions, the Conventions and Protocols are summarized and points of special relevance to the medical services are highlighted. After discussing the interrelationship between IHL and UN peacekeeping missions, the concept of peace enforcement and proposed UN convention protecting UN personnel, it is concluded that there is a need for a document giving a clear definition of the distinct position, obligations and rights of the UN medical services engaged in peace‐promoting missions. Additional tasks in reporting breaches to IHL are also proposed.