Final answer:
Lymphocytes in the blood include B cells, T cells, and NK cells. T cells make up about 80 to 90 percent, B cells about 10 to 20 percent, and these cells collectively account for 20-30 percent of all leukocytes.
Step-by-step explanation:
Lymphocytes, which include B cells, T cells, and Natural Killer (NK) cells, are a crucial component of the immune system and are found in the blood at varying percentages. In human circulating blood, lymphocytes account for about 20-30 percent of all leukocytes.
More specifically, approximately 80 to 90 percent of these circulating lymphocytes are T cells, which are involved in the cell-mediated immune response, and 10 to 20 percent are B cells, which are part of the humoral immune response.
NK cells, another crucial subset of lymphocytes, provide a generalized, nonspecific immunity but their exact percentage in the blood is not mentioned here. It's important to note that while lymphocytes are found in the blood, the majority are located in lymphatic tissues where they are most effective at encountering and responding to pathogens.