红字部分是什么意思？

These cells are almost all derived from hematopoietic stem cells (HSCs) in the bone marrow, which differentiate along branching lineages. Based on their common precursors, immune cells are broadly classified as either myeloid cells, which include phagocytes and most DCs, or lymphoid cells, which include all lymphocytes. The numbers of some of these cell types in the blood are listed in Table 2.1. Although most of these cells are found in the blood, the responses of lymphocytes to antigens usually occur in lymphoid and other tissues and therefore may not be reflected by changes in the numbers of blood lymphocytes.

这些细胞几乎都来自骨髓的造血干细胞，它们沿着分支谱系分化。基于其共同的前体，免疫细胞大体上被分为髓样细胞(包括吞噬细胞和大多数树突状细胞)或淋巴样细胞(包括所有淋巴细胞)。表2.1列出了血液中某些细胞类型的数量。虽然这些细胞中的大多数在血液中发现，但淋巴细胞对抗原的反应通常发生在淋巴组织和其他组织中，因此可能不会通过血液淋巴细胞数量的变化反映出来。

红字部分是什么意思？