Expression of membrane IgM, CD21 and CD32 on lymphocytes in neonatal calves
Bibliographic record
Abstract
Induction of active antibody responses to vaccination is difficult in neonates, due partly to interference by maternal antibodies (IgG) and partly to the limited functionality of the neonatal immune system. Antibody responses by nai?ve B cells are regulated by expression of opposing activating (CD21, membrane IgM [mIgM, the antigen receptor]) and inhibitory receptors (CD32). CD21 binds complement component C3d lowering the threshold of activation, whereas CD32 binds IgG Fc elevating the threshold. Interaction among CD21, CD32 and mIgM determines response and alteration in receptor expression with age might influence the neonate's response to vaccination. An initial cross-sectional study examining receptor expression on blood mononuclear cells of 41 calves of various ages by flow cytometry, was confirmed by a longitudinal study that followed 15 calves from birth to 6 months of age. From birth, there was a significant rise in both the absolute number and percentage of IgM + B cells, which reached adult levels by 6-7 weeks of age. The concentration of mlgM per neonatal lymphocyte was high compared to adults, and >90% of IgM+ lymphocytes expressed both CD21 and CD32 showing potential for response to activating and inhibitory signals. Calf B cells were comparable to those of adults in the intensity of expression of CD21, but expression of CD32 was lower. CD32+ cells comprised two populations: CD14+CD32+ IgM"(44%) and CD14"CD32+ IgM+ (53%) cells, consistent with monocytes and B cells, respectively. Expression of mlgM, CD21 and CD32 was also determined in lymph nodes, spleen and bone marrow of newborn calves by flow cytometry and immunohistochemistry. The percentage of mIgM+ B cells was lower in lymphoid tissues of newborns compared to 7-week-old calves. In newborns >90% of mIgM+ B lymphocytes expressed CD21 whereas only 75% to 83% expressed CD32, suggesting that not all B cells are susceptible to inhibition by maternal antibodies. Follicular dendritic cells were fewer in lymphoid tissues of neonatal calves, and immunohistochemistry revealed additional architectural and quantitative differences. These age-related differences in cell numbers and distribution may contribute to the limited antibody responses in colostrum fed neonatal calves and should be considered in development of vaccination strategies for neonates.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".