Table 1.
CD4+ T helper signals are required of functional memory cytotoxic T-lymphocyte development at higher precursor frequency
| Mice1 | Adoptive transfer (106) | Immunization | Tumour-bearing mice (%) | Lung tumour scoring |
|---|---|---|---|---|
| (a) In the absence of endogenous CD4+ T cells | ||||
| WT | OTI CD8+ T | – | 8/8 (100) | +++++ |
| Iab−/− | OTI CD8+ T | – | 8/8 (100) | ++++++ |
| WT | OTI CD8+ T | DCOVA | 0/12 (0) | – |
| Iab−/− | OTI CD8+ T | DCOVA | 10/10 (100) | +++++ |
| Iab−/− | (CD40−/−) OTI CD8+ T | DCOVA | BL6-10OVA | 10/10 (100) |
| Iab−/− | (CD40L−/−) OTI CD8+ T | DCOVA | BL6-10OVA | 10/10 (100) |
| (b) In the presence of endogenous CD4+ T cells | ||||
| WT | OTI CD8+ T | DCOVA | 0/12 (0) | – |
| CD40−/− | (CD40−/−) OTI CD8+ T | (CD40−/−) DCOVA | 10/10 (100) | +++ |
| CD40L−/− | (CD40L−/−) OTI CD8+ T | (CD40L−/−) DCOVA | 10/10 (100) | ++++ |
The precursor frequency (PF) of wild-type (WT) B6, Iab−/−, CD40−/− or CD40L−/− mice were increased by transferring OTI CD8+ T cells with or without CD40 or CD40 ligand (CD40L) into mice. All the groups were immunized with ovalbumin (OVA) -pulsed dendritic cells (DCOVA) with or without CD40 or CD40L as indicated. Ninety days later, all these groups were intravenously challenged with highly metastasizing BL6-10OVA tumour cells. Twenty-four days later, the percentage of tumour-bearing mice and the grading of metastasis in lungs of tumour-bearing mice were determined. (a) The impact of CD4+ T helper signals on functional memory cytotoxic T-lymphocyte responses was measured by comparing protective immunity in WT B6 and Iab−/− mice. (b) The impact of CD40/40L signal alone on functional memory CTL responses was assessed in CD40−/− and CD40L−/− mice, which were previously transferred respectively with (CD40−/−) OTI CD8+ T and (CD40L−/−) OTI CD8+ T cells before immunizing with (CD40−/−) DCOVA and (CD40L−/−) DCOVA. The data in (a) and (b) are cumulative of two independent experiments, each with four or six mice per group.