The W/W^v mouse strain is heterozygous for two different alleles of the gene encoding the growth factor receptor, c-kit, an important receptor expressed on hematopoietic progenitor cells in the bone marrow. The major defect in these mice is the absence of single lineage of hematopoietic cells. When these mice are challenged with larval Haemaphysalis longicornis ticks, they fail to become resistant to the ticks, in spite of generating high titers of anti-tick IgE antibodies. The cell type missing in the W/W^v mice is most likely:Natural Killer (NK) cells

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The W/W^v mouse strain is heterozygous for two different alleles of the gene encoding the growth factor receptor, c-kit. The c-kit receptor is essential for the development of several cell types, including mast cells. The major defect in these mice is the absence of a single lineage of hematopoietic cells. Given that these mice generate high titers of anti-tick IgE antibodies but fail to become resistant to larval Haemaphysalis longicornis ticks, it suggests that the missing cell type is involved in the allergic response to the ticks, which is typically mediated by IgE antibodies. Mast cells play a critical role in allergic reactions, including the response to tick bites, by releasing histamine and other mediators upon cross-linking of IgE antibodies bound to their surface receptors. The absence of mast cells would impair the local inflammatory response that is necessary to provide resistance to tick infestations. Therefore, the cell type missing in the W/W^v mice is most likely: D) Tissue-resident mast cells

The W/Wv Mouse Strain Is Heterozygous for Two Different Alleles

The W/W^v Mouse Strain Is Heterozygous for Two Different Alleles