幼淋巴细胞系一类在淋巴细胞产生过程中产生的细胞。它们产生自淋巴母细胞，是各种淋巴细胞的直接前体。其大小通常介于10-18微米之间。

A prolymphocyte is a white blood cell with a certain state of cellular differentiation in lymphocytopoiesis. In the 20th century it was believed that a sequence of general maturation changed cells from lymphoblasts to prolymphocytes and then to lymphocytes (the lymphocytic series), with each being a precursor of the last. Today it is believed that the differentiation of cells in the lymphocyte line is not always simply chronologic but rather depends on antigen exposure, such that, for example, lymphocytes can become lymphoblasts.