Countercurrent distribution of lymphocytes from human peripheral blood in an aqueous two-phase system. I. Separation into subsets of lymphocytes bearing distinctive markers

Phase partitioning in space and on earth

In aqueous solution at low concentrations, the neutral polymers dextran and poly(ethylene glycol) (PEG) rapidly form a two-phase system consisting of a PEG-rich phase floating on top of a dextran-rich phase. Biological particles and macromolecules tend to partition differentially between the phases and the liquid-liquid phase interface in these systems. Bioparticle partitioning has been shown to be related to physiologically important surface properties such as membrane charge or lipid composition. Affinity partitioning into the PEG-rich phase can be accomplished by coupling PEG to a ligand having affinity for specific cells or macromolecules. Subpopulations can be identified or separated using multi-step countercurrent distribution (CCD). Incomplete understanding of the influence of gravity on the efficiency and quality of the impressive separations achievable by partitioning, and appreciation for the versatility of this efficient technique, have led to its study for low-gravity biomaterials processing. On Earth, two-phase systems rapidly demix because of density differences between the phases. In low-gravity, demixing has been shown to occur primarily by coalescence. Polymer surface coatings, developed to control localization of demixed phases in low-g, have been found to control electroosmosis which adversely affects electrophoretic separation processes on Earth and in space. In addition PEG-derivatized antibodies have been synthesized for use in immunoaffinity cell partitioning.

A comparison between Fc receptors for IgG1 and IgG3 on human monocytes and lymphocytes using anti-Rh antibodies

In a rosette assay with human erythrocytes equally sensitized with anti-Rh antibodies, the Fc receptor-bearing (FcR) cells are much more numerous among monocytes than among lymphocytes. FcR monocytes could be detected using IgG1 and/or IgG3 antibodies although a higher percentage of FcR cells is observed with sera containing IgG3. FcR lymphocytes are detectable almost only with sera containing IgG3 antibodies. If the anti-Rh antibodies are restricted to IgG1 none or single FcR cells could be found. The application of mixed rosette assay with fluorescein-stained erythrocytes sensitized with IgG3 and unstained red cells sensitized with IgG1 allowed documentation of the presence of receptors for both subclasses on monocytes as well as on lymphocytes although some differences between these cells were observed. Almost all FcR monocytes bind both IgG subclasses, although in different proportions. On the contrary, most FcR lymphocytes bind only or mainly IgG3, but receptors for IgG1 can also be detected.

Separation of lymphocyte subsets by expanding velocity sedimentation of E-rosettes at unit gravity

An expanding velocity sedimentation procedure at unit gravity has been used to separate human lymphocyte subsets on the basis of E-rosette formation. It is shown that the method allows gentle yet efficient separation of T and non-T lymphocytes in a continuous gradient of colloidal silica (Percoll). Less efficient separation was obtained in gradients consisting of polymerized sucrose (Ficoll 70). The technique offers a special advantage in the possibility of separating lymphocytes binding differing numbers of indicator red cells. The method should be generally adaptable to various rosetting techniques, including systems where the indicator cells are attached with weak bonds. As judged by vital staining, the lymphocytes are in excellent condition after the separation.

Natural killer cell activity and antibody-dependent cellular cytotoxicity in newborn infants

The ability of lymphocytes from the peripheral blood of preterm and term infants and adult women and men to mediate natural killing (NK) and K cell activity (antibody-dependent cellular cytotoxicity) was analysed in 4 hours 51Cr-release assays. K 562 cells were targets for NK activity. K cell activity was assayed on antibody-coated rat thymocytes. Lymphocytes from adult male donors were significantly more cytotoxic to K 562 cells than were lymphocytes from adult female donors. Lymphocytes from both preterm and term infants had significantly lower NK and K cell activity than lymphocytes from adult donors. During the first month of life no increase in NK activity or K cell activity occurred in 7 infants who were re-examined. It is concluded that neither NK nor K cell activities are fully developed during the first month of life.