The monocyte/macrophage cell lineage is an essential component of host defense. Functional deficiencies have been described in neonatal monocytes, but knowledge of membrane antigen and receptor ligand expression in neonatal monocytes is incomplete. In this study, antigen and receptor ligand expression of cord blood monocytes (CBM) was examined and compared to adult peripheral blood monocytes (PBM). Leu-M3 and Leu-M5 antigens were shown to be present on all CBM. Using dual fluorescence microfluorometry, the percentage and intensity of expression of HLA-DR, CD4 antigens, Fcγ and IL-2 receptors (IL-2R) on Leu-M3⁺ and Leu-M5⁺ CBM were compared to PBM. A lower percentage of expression of HLA-DR⁺ (87 ± 3% vs. 95 ± 1%, p = 0.02) and FCγRII⁺ (96 ± 1% vs. 99 ± 0.2%, p = 0.04) was noted on CBM. CD4, FCγRI, and FCγRIII expression on CBM were comparable to PBM. LPS stimulation of CBM induced IL-2R expression and enhanced HLA-DR antigen expression as seen previously on PBM. These findings indicate that CBM are phenotypically comparable to adult PBM with deficiencies localized only to a few specific areas.

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The study of the cellular immune components of human milk is essential in the understanding of the role human milk may play in protecting the nursing infant against infection. We have investigated some phenotypic characteristics of breast milk macrophages (BMM) and have compared them to the characteristics of adult peripheral blood monocytes (PBM) by using dual parameter flow microfluorometry. Most BMM expressed the monocyte/macrophage markers Leu-M3 and Leu-M5. The latter marker was present in high density (bright) on BMM, but the density of expression of Leu-M3 was higher on PBM than on BMM [median fluorescence intensity (MFI) 409 ± 105 versus 203 ± 106, p = 0.02]. The percentage of BMM (98 ± 2) that expressed the HLA-DR antigen did not differ significantly from PBM, but the density of expression was higher on BMM (MFI 318 ± 56 versus 264 ± 41, p = 0.03). The HLA-DR expression of BMM was further enhanced after incubation with interferon-γ for 36 h; however, receptor for interleukin-2 could not be induced on BMM by this treatment. The expression of the three classes of FcγR was lower on BMM than on PBM, in percentage (FcγRI 56 ± 23 versus 79 ± 17%, p = 0.02), density of expression (FcγRIII MFI 71 ± 20 versus 153 ± 73, p = 0.002), or both (FcγRII 74 ± 22% versus 94 ± 12%, p = 0.02, and MFI 115 ± 53 versus 202 ± 59, p = 0.003). These findings help to define the BMM as a Leu-M3+ (dull), HLA-DR ± (bright), phenotypically mature macrophage with a specifically low expression of the FcγR ligands. These cell surface characteristics could be ontogenic in nature, or could reflect pregnancy-induced down-regulation of the maternal immune system.

In this paper, a new algorithm for the calculation of the frequency-dependent parameters of arbitrarily shaped power cable arrangements is presented. The algorithm uses digital images to discretize the cable geometry and partial subconductor equivalent circuit method to estimate the cable parameters. The proposed methodology adapts itself to the physical memory of the computer, allowing the program to partition the partial subconductor impedance matrices when their sizes exceed the available physical memory. Coaxial cables and sector-shaped cables are studied, and the results are compared with those obtained from analytical formulae and the finite-element method.

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