Fig. 6

Fig. 6

MLCs Transfer Soluble Antigens to cLCs through Apoptosis-Phagocytosis Axis

(A) Time-lapse imaging on the scales of the OVA-647-treated Tg(drl:mCherry-T2a-Cre;mpeg1:loxP-DsRedx-loxP-GFP) fish. The time-lapse begins at 1 dpc and images for 12 h. White arrows indicate that an apoptotic OVA-647⁺ (blue) MLC (red), which is subsequently phagocytized by three nearby cLCs (green). Scale bar, 20 μm.

(B) Quantification data show the percentages of apoptotic OVA-647⁺ and OVA-647^- MLCs in the same scales during time-lapse imaging (n = 5 fish).

(C) Images indicate a typical cLCs (green) with OVA-647 (blue) and MLCs debris (red) inside in a living Tg(drl:mCherry-T2a-Cre;mpeg1:loxP-DsRedx-loxP-GFP) fish after OVA-647 treatment. Scale bar, 25 μm.

(D) Quantification data show the percentages of cLCs containing OVA-647 and MLC debris inside to total OVA-647⁺ cLCs at different time points (n = 4 fish).

(E) A schematic diagram shows the experimental procedure of MLC-depletion strategy using the NTR-MTZ system. Control Tg(krtt1c19e:mCherry-T2a-CreER^T2;mpeg1:loxP-DsRedx-loxP-GFP) and experimental Tg(krtt1c19e:mCherry-T2a-CreER^T2;mpeg1:loxP-DsRedx-loxP-GFP-NTR) fish (both are treated with 4-OHT for 5 days during early stage) are immersed in 5 mM MTZ for 24 h transferred to system water containing 2.5 μg/mL OVA-647 for another 24 h (OVA 1 dpi), and finally switched to fresh system water.

(F) Quantification data show cell densities of MLCs and cLCs in control (GFP MLCs; GFP cLCs) and experimental fish (NTR MLCs; NTR cLCs) at different time points (each group, n = 4 fish).

(G) Quantification of the percentages of OVA-647⁺ MLCs and cLCs in control (GFP MLCs; GFP cLCs) and experimental fish (NTR MLCs; NTR cLCs) (each group, n = 4 fish).

Data are represented as mean ± SD, ^∗∗p < 0.01, ^∗∗∗p < 0.001, ^∗∗∗∗p < 0.0001.