T-Cell Dependency of T-Independent (TI) Antigens: Antibody Response to Blood Group A-Antigen Requires CD4 T-Cells and CD40/CD40L Interaction
Bibliographic record
Abstract
Introduction: Polysaccharides are considered TI antigens capable of eliciting antibody secretion without T-cell help. TNP-Ficoll is used as a model TI (type 2) antigen, but detailed mechanisms of B-cell responses remain unclear. We studied a T-cell role in the antibody response to polysaccharides, using a clinically relevant ABO antigen in its natural form. Methods: Mice (4-8 week-old) received three standardized immunizations (days 0- 7- 14) with human blood group-A erythrocyte membranes, TNP-Ficoll or sperm whale myoglobin (SPWM; protein); some groups received first injection in complete Freund's adjuvant then two boosts without adjuvant. For T-cell depletion studies, anti-CD4 (clone GK1.5) or isotype control were injected on day -1-0- +1. To further characterize direct and indirect interaction of CD40/CD40L, CD40L KO mice were injected with anti-CD40 (clone IC10) or isotype control in order to activate or block CD40 on B cells; CD40 KO mice were injected with mouse rCD40-Fc fusion protein to activate T-cells which in turn may activate B-cells through soluble factors. TLR contribution was studied in MyD88 KO. Anti-A antibodies were measured in plasma at day -1-14-21 by hemagglutination and ABO-ELISA, and TNP and SPWM antibodies by ELISA. Results: Natural anti-A antibodies were undetectable on day -1 in all groups, whereas anti-TNP antibody was present in young mice. A-erythrocytes elicited a substantial antibody response, which was abrogated by CD4 T-cell depletion (fig 1), including IgM (fig 2), whereas of SPWM antibodies, only IgG was absent with normal or low IgM and IgA. Antibodies to TNP-Ficoll were comparable in CD4-depleted vs. control mice. Similarly there were no differences in response to secondary A-antigen immunization when CD4 cells were depleted in pre-immunized mice. Anti-A antibodies were significantly reduced in CD40L KO, and further diminished with anti-CD40 antibody; no reduction was seen in MyD88 KO mice. Conclusions: This study clearly demonstrates that antibody response to A-antigen requires CD4 T-cells. Although polysaccharides may not stimulate MHC class II-dependent T-cell help, the presence of activated CD4 T-cells and their interaction with B-cells through CD40-CD40L (fig 2) is critical for B-cells to become antibody secreting cells. These findings have major implications for ABO-incompatible and xenotransplants.[Figure 1][Figure 2]
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 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) | 0.000 | 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 teacher head, 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".