SOURCE OF ELEVATED SERUM ENZYME ACTIVITIES IN PATIENTS WITH MEGALOBLASTIC ERYTHROPOIESIS SECONDARY TO FOLIC-ACID DEFICIENCY

Leukaemic peripheral blood plasma and bone marrow plasma: comparison of influence on lymphocyte proliferation

Peripheral blood plasma from some children with untreated acute lymphoblastic leukaemia (ALL) exerted an inhibitory effect in vitro on phytohaemagglutinin-induced lymphocyte transformation of normal peripheral blood lymphocytes. This occurred at concentrations beyond that required for optimal response as judged by reduction of blast cell formation and tritiated thymidine and tritiated uridine incorporation into DNA and RNA, respectively. In contrast, bone marrow plasma from these patients was non-inhibitory or contained significantly less inhibitory activity. Bone marrow plasma from the majority of healthy controls was superior to their peripheral blood plasma in enhancing phytohaemagglutinin-induced mitogenesis. The difference between an individual's bone marrow- and peripheral blood-derived plasma in enhancing proliferation of patient and healthy control cells was significantly greater amongst the patients than the healthy control group; this was attributed mainly to the increased inhibitory activity of ALL peripheral blood plasma compared with normal plasma. Medium conditioned by phytohaemagglutinin-stimulated normal peripheral blood lymphocytes was effective in neutralizing the inhibitory activity of ALL peripheral blood plasma. Taken together, these in vitro results are at least suggestive that in vivo, in healthy subjects, the rapidly proliferating cells in the bone marrow and the 'resting' blood cells in the circulation may be under the influence of a fine balance of different types and/or levels of humoral growth stimulatory and inhibitory factors and that in ALL an unstable balance of these factors exists. The decreased proliferation of circulating blast cells compared with bone marrow blasts in ALL may be attributed, at least in part, to exposure to the different levels of inhibitor(s) in the circulation and bone marrow as demonstrated in vitro by our results.

Enzymes in peripheral and bone marrow serum in patients with cancer

Lactic dehydrogenase (LDH), glutamic-oxalacetic transaminase (GOT), and acid and alkaline phosphatase activities in bone marrow and in cubital vein serum were compared. For patients without cancer, marrow serum LDH attained levels four times as high, and GOT and alkaline phosphatase, levels twice as high as those normal for cubital vein serum; levels of acid phosphatase were the same for both sources. For patients with cancer, significant increase of enzyme levels over reference levels depends on the tumor origin and on the presence and localization of metastases. Marrow enzyme levels may become elevated with or without concurrent elevation in cubital vein serum. Concurrent elevations were found with colonic carcinoma and lymphoid leukemia, and noncurrent elevations, with prostatic cancer, myeloid leukemia, and myeloma. A nonconcurrent elevation of marrow enzymes indicates that the origin of the enzyme is in the marrow, whereas with concurrent elevation, the source of the enzyme may be another organ.

Plasma lactate dehydrogenase in megaloblastic anaemia

Raised plasma lactate dehydrogenase (LDH) values were found in 26 patients with marked megaloblastic anaemia due either to vitamin B(12) or folic-acid deficiency or a combination of these factors.Minor megaloblastic changes were not usually accompanied by plasma LDH elevation. Serial LDH estimations were as valuable as serial reticulocyte counts in assessing the response to physiological doses of folic acid and therefore in deciding whether megaloblastic anaemia is partially or completely due to folic acid deficiency.