PMC8312240_01
Tissue biopsies and NK function testing. (a) Diagnostic bone marrow sample demonstrating hypercellular marrow with fibrosis and 50-60% T-cell burden (anti-CD3 immunostain, x40 magnification). (b) Post-CHEOP trephine demonstrating normalisation of cellularity and reduction in the T-cell infiltrate (anti-CD3 immunostain, x40 magnification). (c) Post-G-CSF trephine with an increase in T-cell infiltration (anti-CD3 immunostain, x40 magnification). (d) Liver biopsy specimen showing polymorphous lymphocytic infiltration and areas of necrosis (haematoxylin and eosin stain, x60 magnification). (e) Liver biopsy specimen after diagnosis of HLH demonstrating increased macrophage activity and haemophagocytosis (arrow) (haematoxylin and eosin stain, x100 magnification). (f) Natural killer cell cytotoxicity following heterologous bone marrow transplantation was assessed using 51Cr release assay. Thus, peripheral blood mononuclear cells were isolated from the whole blood using Ficoll, incubated overnight in a complete cell culture media in the absence or in the presence of 100 U mL-1 IL2. The cells were then mixed with Na2
[51]CrO4-labelled MHC class I-deficient K562 target cells at the indicated Effector:Target (E/T) cell ratios normalised for % natural killer cells (CD16+/CD56dim+/CD3-). After 4 h of co-incubation at 37 C, the cells were centrifuged at 500 g for 4 min, and the released 51Cr was measured in the supernatant using gamma counter. Spontaneous 51Cr release from K562 cells was assessed in the absence of PBMC, and the total (100%) 51Cr content was estimated using Triton X-100 lysed cells. The percentage-specific 51Cr release was calculated using the following formula: ([Experimental Release - Spontaneous Release]/[Total Release - Spontaneous Release]) x 100. Left: natural killer cell cytotoxicity at the time of diagnosis. Right: natural killer cell activity 18 months later, after heterologous bone marrow transplantation.
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Bone marrow biopsy demonstrated a moderately hypercellular marrow with reduction in normal trilineage haematopoiesis and multifocal interstitial lymphoid aggregates comprising small, mature CD3+ T cells (Figure 1a) without haemophagocytosis.