Quantitative analysis of leukocyte membrane antigen expression on human fetal and cord blood: normal values and changes during development.

We studied the antibody binding capacity (ABC) of various cell-surface antigens in normal human fetuses and term neonates on lymphocyte, monocyte, and polymorphonuclear (PMN) cells by quantitative flow cytometry also designated by quantimetry. Analysis of changes of expression level on these leukocytes during the developmental process was also investigated. The results indicated that the ABC values of most studied markers change during the maturational process. The ABC of lymphocyte-associated antigens studied such as CD5 and CD7 showed only a decrease from fetus to adult, whereas according to the type of molecule on monocyte and PMN there was either an increase or a decrease of ABC values dependent on the stage of the developmental process, from fetus to neonate or from neonate to adult. However, the ABC values of leukocyte membrane antigens such as CD16, CD46, and CD55 on all leukocytes and CD11b, CD11c, and CD35 on myeloid cells did not change. Their expression level was already mature in fetuses compared with adult cells. In addition, in this quantimetric approach, the analysis of the results for CD11a and CD8 suggested that the changes of CD11a expression level on lymphocyte subsets can depend on one mechanism, whereas there are probably at least two for CD8. Furthermore, the expression patterns of CD5, CD7, and CD11a change during maturation. We concluded that, even if the neonate response pattern to immunological challenge differs from an adult and this is based primarily on the relative numbers and functional activity of lymphocyte T subsets (especially TH1/TH2) and their cytokine profiles, these quantitative and qualitative phenotypical differences might also contribute to explain the functional peculiarities of leukocyte fetal and cord blood cells. All these findings support the notion of immaturity and maturity of ABC expression.

Quantitative analysis of leukocyte membrane antigen expression: normal adult values.

In this paper the normal ranges of the expression of various differentiation antigens, referred to by their cluster of differentiation (CD) numbers, are described on the lymphoid, monocytic, and polymorphonuclear (PMN) blood populations in normal healthy individuals. The values expressed as antibody binding capacity per cell (ABC/cell) are related to the density of antigenic molecules expressed by these cells. These values have been quantitated by the quantitative indirect immunofluorescence (QIFI) test which renders the ABC/ cell values for the different antigens directly comparable and defines a "league table," i.e., an enumeration of antigen expression on the three main cell types studied. The values for occasional antigen that are expressed differently in adults and the elderly or men and women (CD5, CD8, and CD18) are also shown. Furthermore, the QIFI test is used in two-color immunofluorescence for defining the subset heterogeneity within the T lineage for the CD2 and CD7 antigen within the separately analyzed CD45RA and CD45RO subsets. These quantitative immune phenotype analyses, also referred to as quantimetry, show variations in ABC values if different monoclonal antibodies (MAbs) are used, although these differences are frequently minor. Therefore, using whole blood and well-characterized MAbs, we established values of antigen density in normal adults which can be regarded as control values for the various pathological conditions where CD antigen expression may be altered.