Immunological alterations associated with Plasmodium vivax malaria in South Korea

Various haematological and immunological studies on patients infected with Plasmodium vivax were undertaken, at diagnosis (day 0), after treatment wit h chloroquine but during primaquine treatment (day 10) and after all treatm ent (day 59), in South Korea (where there has been a recent and abrupt incr ease in the incidence of such infection). The main aims were to gain an und erstanding of the haemato-immunological alterations of this malarial infect ion, both before and after treatment, and to identify at least one useful m arker for the diagnosis and post-treatment monitoring of P. vivax malaria. Thirty-eight patients with P. vivax malaria were compared with 20, apparent ly healthy controls. At diagnosis, the patients had lymphopenia, marked eos inopenia (the eosinophil count being correlated with the platelet count) an d thrombopenia. Cells of most of the lymphocyte subsets investigated [i.e. CD3(+), CD8(+) CD19(+) CD56(+), CD3(-)/CD56(+) and CD8(+)/CD56(+) but not C D4(+), CD3(+)/CD56(+). or CD25(+)] were significantly less common among the lymphocytes of patients at diagnosis than among those of the controls. Aft er initiating treatment, the numbers of CD19(+) lymphocytes gradually incre ased (to normal values by day 59), whereas those of CD3(+)/56(+) lymphocyte s remained abnormally low throughout the follow-up period. The proportions of lymphocytes identified as CD4(+) appeared to be unaffected by treatment. Although serum concentrations of IgE (and, to a lesser extent, IgM) were e levated in the patients at diagnosis, they were subnormal on day 10 post-tr eatment and normal at the day-59 follow-up. Serum concentrations of IgG and IgA in the patients were always found to be similar to those in the controls. At diagnosis the serum concentrations of complements C3 and C4 were significantly elevated in the patients. C3 rema ined at the same high concentration during follow-up but the concentration of C4, like that of IgE, was found to be subnormal on day LD and normal 7 w eeks later. The level of parasitaemia (%) was only found to be significantl y correlated with haemoglobin concentration. The observation of eosinopenia with elevated IgE and C4 could be a useful i ndicator of P. vivax malaria, and treatment response could be followed by s erial monitoring of serum concentrations of IgE and C4.