Fig. 2: Kell knockout in BEL-A reticulocytes: effects on host receptor expression, parasite invasion, and enzymatic activity.

A Immunofluorescence staining and quantification of protein expression levels for the specified host receptors in reticulocytes derived from unedited and Kell-null BEL-A cells. The staining demonstrates comparable expression profiles between the two cell types. B, C Flow cytometry histograms and immunoblot analyses revealed no significant alterations in the expression levels of the indicated host receptors (Spectrin, Glycophorin A, Xk, Band 3, and Glycophorin C with loading control GAPDH) between reticulocytes derived from unedited and Kell-null BEL-A cells, confirming that the Kell knockout does not impact other key receptor expressions. D, E Bar graph and representative Giemsa-stained cytospins illustrating parasite multiplication rate (PMR), calculated as the ratio of ring-stage parasites to added mature schizonts, in reticulocytes derived from WT and Kell_null BEL-A cells. The invasion was assessed 10 h post-infection by manual counting of ring-stage parasites on Giemsa-stained cytospins. Statistical significance was determined using a two-tailed student’s t-test, where *** indicates p  ≤  0.001 and “ns” denotes non-significance (p  >  0.05). F Schematic representation (created by Biorender.com) illustrating Kell’s metalloprotease activity in BEL-A WT and Kell-null reticulocytes, highlighting the enzymatic role of Kell in these cell models. G Bar graph displaying enzymatic (protease) activity in reticulocytes derived from WT and Kell-null BEL-A cells. All experiments were conducted with at least three independent biological replicates (n = 3), and the data were presented as the mean ± standard deviation (SD). Statistical significance is denoted as *p < 0.05 and **p < 0.01 calculated through the student’s t-test.