Cellular immunity in human milk

Anti-inflammatory characteristics of human milk: how, where, why

When first proposed, the hypothesis that human milk was anti-inflammatory was supported by 2 observations: poor function of milk leukocytes and the presence in milk of components that could modify inflammatory processes. This hypothesis is now supported by studies documenting anti-inflammatory effects in animal models and suppression of humoral and cellular components of inflammation in vitro. To date, two mechanisms have been demonstrated: alteration of leukocyte function and modification of cytokine biology. It is not clear whether these mechanisms are only topical effects in the digestive tract, or whether absorption of milk components results in systemic effects. While inflammation benefits the host as a defense mechanism and precursor to immune responses, it also contributes to the clinical manifestations of illness and is an important early component of wound-healing responses that result in scar. The biological effects of milk's anti-inflammatory character may be to minimize clinical symptomatology without losing immunoresponsiveness for the breast-fed infant, and to minimize scar formation during healing responses.

Adhesion molecules and lymphocyte subsets in milk and blood of periparturient Holstein cows

Migration of leukocytes into the mammary gland is an essential element of resistance to infection which is likely influenced by expression of adhesion molecules. The contribution of subsets to mammary gland resistance remains unclear. Mononuclear cells from milk and blood of dairy cows were examined for variation in CD4+, CD8+, and WC1+ (Workshop Cluster 1; marker for gammadelta T cells) lymphocyte phenotypes and expression of LFA-1 and L-selectin at several time points during the periparturient period and at Week 16 of lactation. Proportions of CD4+ T cells were higher (p < or = 10.05) in blood than milk at all times between Week 0 and Week 16 relative to calving; the inverse was true of CD8+ cells. Expression of L-selectin was lower (p < or = 0.05) on CD4+ cells and higher on CD8+ cells from milk. The WC1+ subset was more frequent in blood than in milk except at calving when the opposite was true. After calving, proportions of L-selectin+ WC1+ cells decreased steadily to Week 16. Expression of LFA-1 was examined on mononuclear cell populations and found to be lower on milk cells and did not vary over time. We conclude that proportions of T cells subsets differ significantly between blood and milk, particularly around calving. Corresponding variations in L-selectin expression may indicate a role for this molecule in regulating the movement of CD8+ and WC1+ T cells into the bovine mammary gland.

Immunobiology of the mammary gland

The mammary gland is a complex organ that provides neonatal offspring with milk for nourishment and disease resistance. Specific and innate immune factors associated with mammary gland tissues and secretion also play a vital role in protecting the gland from infectious disease. Through genetic selection and technological advances in milk removal, the bovine mammary gland yields for more milk than is needed to nourish the newborn calf. This excess is the basis of the dairy industry. Factors associated with the intense management of dairy cattle can profoundly affect mammary gland immunity and the ability of the host to resist mastitis. Technological advances in immunology have led to the availability of new research tools that can facilitate the study of mammary gland immunity and disease pathogenesis. In recent years, considerable research effort has focused on enhancing the natural defense mechanisms of the mammary gland during periods of heightened susceptibility to disease. This paper provides a comprehensive overview of mammary gland immunity with special emphasis on the bovine system. The underlying mechanisms of disease susceptibility and development of potential immunoregulatory strategies to control mastitis are discussed.

Distribution of lymphocyte subsets in rat milk from normal and Trichinella spiralis-infected rats

We have shown that T. spiralis-specific T lymphocytes can mediate maternal-to-neonatal immunity during lactation. This study addresses the change of lymphocyte populations in rat milk during normal and disease conditions. Two color flow cytometric analysis was performed for milk lymphocytes. T cells (OX19+) made up 45% of rat milk lymphocyte population. T helper cells (Th) composed 35% of total T cells while T cytotoxic/suppressor (Tcs) cells constituted 34%, giving a Th/Tcs ratio of 1.03. The corresponding ratio Th/Tcs in peripheral blood was 2.8. Approximately 21% of OX8+ cells in rat milk were OX19- natural killer (NK) cells. When using the monoclonal antibody 3.2.3 (NKR-P1), 43% of lymphocytes in control rat milk and 14% of blood lymphocytes were NK cells. This indicates a selective passage of these cells into milk. In T. spiralis-immunized rats, the percentage of total T cells was slightly decreased; however, Th and Tcs cells were consistent as compared to control milk. The percentage of NK cells (OX8+OX19-) in milk from T. spiralis-immunized rats was significantly higher than that from control milk (65% vs. 21%, respectively, P less than 0.01). This result was confirmed using the monoclonal antibody 3.2.3 which showed that milk from immunized rats contained 63% NK cells compared to 43% in normal milk (P less than 0.01). This study suggests that NK cells are selectively passaged into rat milk and T. spiralis infection induces an increase of NK cells in milk.

Infant feeding effects on flow cytometric analysis of blood

Flow cytometric analysis was performed on purified mononuclear cells isolated from whole blood samples of 11 adults, 7 breast-fed (BF) infants and 11 formula-fed (FF) infants, mean ages 34.2 +/- 4.3 years, 6.3 +/- 1.3 months, and 6.2 +/- 1.2 months, respectively. Infants were receiving at least 70% of calories from formula or breast milk. Infant mononuclear cell populations contained a higher percentage of lymphocytes and a lower percentage of monocytes compared with adults. Within the lymphocyte population, infants had a higher CD4+/CD8+ ratio (T helper-inducer/T cytotoxic-suppressor), a higher percentage of CD19+ (pan B) and CD4+ cells, and a lower percentage of CD8+ and CD16+ (natural-killer) cells compared with adults. CD3+ (pan T) and CD4+ lymphocyte percentages were higher and CD19+ lymphocyte percentages were lower in FF compared with BF infants. Although sample size is small, our data indicate that diet may influence lymphocyte subset distribution during infancy when the majority of calories is derived from infant formula or human milk.

Lymphocytes bearing the T cell receptor gamma delta in human breast milk

Lymphocytes bearing the T cell receptor gamma delta (TCR-gamma delta) were searched for in human early milk lymphocyte suspensions by two colour cytofluorimetric analysis. It was found that the proportion of TCR-gamma delta+ cells was twofold greater in colostrum than in either autologous or heterologous blood samples. Additional studies are needed to determine whether this particular subset of lymphocytes is involved in the lactation transmission of cellular immunity.

Maternal-fetal interactions on the regulation of the autoimmune response

Adult female rats were immunized with 5 mg or 25 mg of modified rat male accessory glands (MRAG) incorporated to complete Freund's adjuvant (CFA) before, during, and after pregnancy. The mothers and litters were exchanged between the experimental and normal groups. The offspring were brought up to 20 days of age and immunized with 5 mg of MRAG-CFA and 5 mg of human serum albumin (HSA)-CFA. Anti-MRAG antibodies were detected in the offspring brought up by the immunized mothers and the titers were similar to those of the foster mothers whereas in the offspring of the experimental group fostered by normal mothers antibodies to MRAG were not detected. The DTH performed in the offspring 13 days after the immunization was significantly diminished in male and female offspring from the 5 mg and 25 mg experimental group fostered by normal mothers (P less than 0.0005 for all groups). Similar results were found when the offspring from normal mothers were suckled by mothers immunized with MRAG-CFA. To assess whether MRAG or HSA administered to female rats reached the offspring via the placenta or the milk, female rats were immunized with 3 mg of 125I-MRAG-CFA or with 3 mg of 125I-HSA-CFA. When radioactivity was measured in neonates (n = 11) that were suckled by the 125I-MRAG-CFA immunized mothers, the specific activity was 116 in stomach (0.4 micrograms of MRAG) and 940 in the total organs (3.8 micrograms of MRAG).(ABSTRACT TRUNCATED AT 250 WORDS)

Human breast milk T lymphocytes display the phenotype and functional characteristics of memory T cells

Naive (unsensitized) and memory (antigen-primed) T cells can be phenotypically distinguished on the basis of the high or low intensity with which they express a number of immunologically relevant lymphocyte membrane antigens, including CD45R, CDw29, UCHL1, LFA-1, LFA-3, CD2 and Pgp-1. Here we report that in contrast to the two major T cell subsets found in the blood, milk T lymphocytes are almost exclusively composed of the one which exhibits the CD45Rlow, CDw29, UCHL1, LFA-1high memory T cell phenotype. In addition, while milk and autologous blood cells expressed similar levels of CD3 surface antigens, CD2 and ICAM-1 expression was approximately twofold greater on the milk T lymphocytes. This agrees with the finding that whereas colostrum T cells respond poorly to PHA, they proliferate and produce interferon-gamma normally when stimulated with either the anti-CD3 or anti-CD2 monoclonal antibodies. The selective colonization of the mammary gland during lactation by a population of T lymphocytes which displays the phenotype and functional characteristics of memory T cells may be one of the mechanisms whereby the suckling infant benefits form its mother's immunological experience.

Popliteal lymph node enlargement induced in syngeneic hosts by T cells from foster-nursed mice

Splenocytes from adult F1 mice were assayed for their capacity to induce popliteal lymph node enlargement (PLNE) when inoculated in the footpad of identical or reciprocal F1 hosts. The results obtained showed that: (i) T Lyt 1+ splenocytes from adult F1 hybrids were able to induce a significant PLNE when inoculated in reciprocal but not in identical F1 hosts. (ii) Foster-nursing of F1 hybrids on mothers from the paternal strain was able to induce permanent alterations in the ability of their T splenocytes to induce PLNE: Lyt 1+ splenocytes were able to induce significant PLNE in identical but not in reciprocal F1 hosts. Thus, the ability of T splenocytes from foster-nursed F1 hybrids to induce PLNE resembled that observed in reciprocal F1 hybrids nursed by their own mothers. (iii) PLNE was accompanied by cell proliferation involving host B and T lymphocytes. (iv) This PLNE could be detected using F1 hybrids from parental strains differing or not at H-2 antigens but involving a parental strain expressing the stimulatory Mlsa allele and a parental strain bearing the nonstimulatory Mlsb allele while it was not observed in F1 hybrids from parental strains sharing Mlsa antigens.

Maternal influence on the immune response: SMLC reactions between identical and reciprocal F1 hybrids and the role of lactation

Identical and reciprocal adult F1 mice from different strain combinations, either nursed on their own mothers or foster-nursed on mothers from the paternal strain, were used to carry out SMLC assays. The results obtained showed that: (1) in vitro proliferation of F1 T cells was significantly different when splenocytes from identical versus reciprocal hybrids were used as the stimulatory population, splenocytes from one of the members of the reciprocal pair being able to induce higher proliferative responses of T cells from both identical and reciprocal F1 hybrids; (2) foster-nursing of F1 hybrids on mothers from the paternal strain was able to induce permanent alterations in the ability of their splenocytes to stimulate the proliferation of responder F1 T cells. The stimulatory ability of splenocytes from foster-nursed hybrids was indistinguishable from that observed in the reciprocal F1 combination nursed by its own mother. The existence of a maternal effect acting through milk on the outcome of self recognition in the litter is discussed.

In vitro suppression of murine blastocysts growth by sera from women with reproductive disorders

Early mouse embryos at the two-cell stage were cultured in medium supplemented with sera from women with primary and secondary multiple spontaneous abortions and with long term unexplained infertility as compared to sera obtained from normal fertile women and pooled human male sera. On the basis of microscopic observation and uptake of 3H-thymidine we report a relationship between reproductive histories and the presence of a serum embryo inhibition factor in eight of ten sera samples from women with primary habitual abortions, six of ten sera from women with secondary habitual abortions, and ten of ten sera from women with unexplained infertility. This activity occurs independently of positive maternal antipaternal lymphocytotoxicity. Fractionation of serum samples by ammonium sulphate precipitation, resulted in removal of the embryo-inhibition factor with the IgG fraction in four of five primary habitual abortion cases and in two of five secondary habitual abortion patients, but not in the case of unexplained infertility. We propose that the appearance of such inhibition factor may be of relevance in the etiologies discussed in this paper and may possibly provide the basis for a new classification of idiopathic spontaneous habitual abortions, i.e. positive or negative for the embryo inhibition factor.