Activated and memory T lymphocytes in human milk

Abstract

Since activated macrophages and cytokines are found in human milk (HM), a flow cytometry study was conducted to determine whether T cells in HM display phenotypic markers of recent or previous activation. HM was collected during the first 3 d of lactation. The Paint-a-Gate program was used to optimize gating on the lymphocyte population. A mean & 1 SD of 4 & 3% of total HM leukocytes were lymphocytes and 96 f 3% were macrophages and granulocytes (N = 33 subjects). HM lymphocyte populations were further analyzed in five subjects. T cells (CD3+) represented 83 f 11% and B cells (CD19') were 6 & 4% of HM lymphocytes. The mean CDWCDB ratio of T cells in HM was 0.88 (range 0.40-1.25). This ratio was significantly decreased compared to the peripheral blood (PB) of control adults (P < 0.02) and postpartum women (P < 0.021, due mostly to a significant increase in CD8+ CD3+ cells in HM compared to the PB of control adults (P < 0.002) and postpartum women (P < 0.05). T cells bearing markers of recent activation were significantly increased in HM compared to the PB of control adults: 85 f 7% of CD3+ cells in HM were HLA-DR+ (controls, 10 f : 4%; P < 0.001), and 15 k 6% of CD3+ cells in HM were IL-2R+ (controls, 6 f 2%; P < 0.001). Subpopulations of CD4+ and CD8+ cells in HM defined by the T200 isoforms CD45RA and CD45RO were markedly altered compared to PB, indicating a striking shift from virginal to antigen-primed (memory) T cells in HM and suggesting certain functional capacities for these cells. Virtually all CD4+ cells (99.8 2 0.4%) and 92 f 5% of CDB+ cells in HM were CD45RO+ (vs. 71 f 12% and 50 f lo%, respectively, in the PB of postpartum women; P < 0.001). CD4+ and CD8+ cells expressing CD45RA were correspondingly markedly reduced (P < 0.001). This phenotypic pattern of T cells in HM may result from T cell activating substances in HM and/or selective homing of T cells to the breast. Conversely, activated T cells in HM may be responsible for cytokines in HM. These activated and memory T cell populations may be transferred to the infant via breastfeeding.Key terms: Human milk immunology, T lymphocyte subsets, flow cytometry, markers of activation, leukocyte common antigen isoforms It has been known for some years that leukocytes are part of the immunologic system in human milk (HM) (42,121. About 3 million leukocytes are found in each milliliter of HM produced during the first few days postpartum, and the principal types of leukocytes found in HM during that period are neutrophils (40-60%), macrophages (30-50%), and lymphocytes (5-9%). T cells comprise 60-73% of HM lymphocytes based on the capacity to form rosettes with sheep erythrocytes [12,34], and the thermostability of these rosettes suggests that HM T cells are activated [341. The

Maternal immunisation: collaborating with mother nature

“…Breast milk contains neutrophils, macrophages, and lymphocytes (115). Common infections 17 increase the number of total leucocytes in breast milk but whether similar changes occur post-18 immunization is unknown (116).…”

Broad Neutralizing Antibodies to HIV Env and Other Complex Viral Antigens from Vaccinated Cows

“…The results showed that the cows were capable of producing broad cross-subtype strain neutralizing activity that was transferred at high titer (1: 1 × 10 6 ) into colostrum. These antibodies include specificities that bind the highly conserved CD4bs on HIV Env trimmers and compete with the VRC01 mAb selected for analysis in the AMP trial and related BrNAbs, like b12 [40]. Heydarchi et al showed that bovine antibodies from vaccinated cow, not only bind to CD4bs but also can neutralize HIV infectivity through this region [41].…”

“…Our experience with HIV Env antibodies suggests potent neutralizing IgG antibodies required a relatively long maturation time when produced by pregnant cows [40]. Furthermore, the large body mass of the cows may require much more vaccine compared to other animals [40,[100][101][102]. Additionally, highest concentrations of colostrum antibody are found in the first colostrum and this must be collected immediately after the unpredictable event of calving.…”

“…In general, quantitative and qualitative batch-to-batch variation is the another potential obstacle with the use of polyclonal antibodies from animals [104]. Though passive immunization with the bovine polyclonal antibodies can prevent or control infection [26][27][28][29][30][31]40], a general problem for polyclonal antibodies is that a large portion of stimulated antibodies will target non-neutralizing epitopes and titer of specific antibodies may be low [42]. However, one strategy to cope this problem may be the production of the monoclonal BrNAbs targeting conserved epitopes among different subtypes of a virus.…”

Breastfeeding-related maternal microchimerism

“…Breast milk lymphocytes consist mainly of an extra-lymphoid memory cell population 6 . Most CD4 + and CD8 + T cells are effector memory cells 7,8 . Up to 6% of breast milk cells are progenitor or stem cells of haemopoietic, mesenchymal and neuroepithelial lineages 9,10 .…”