FLOWCYTOMETRY IN LEPTOSPIROSIS

SUMMARY: Differential count of leucocytes and six lymphocyte populations and subpopulations were investigated by flow cytometry in fourteen cases with leptospirosis. Marked granulocytosis and lymphopenia were found in 100%. The percentage of the monocytes was significantly decreased (mean 6,65%; 0,7 to 14,0%; sd 5,49). Immunophenotypization of lymphocyte populations and subpopulations by flow cytometry was revealed prevalent tendencies for decreasing of the number of total T-lymphocytes, T-helpers, T-suppressors, T-helpers/T-suppressors index; increasing of the number of the activated T-lymphocytes, subpopulation of NK cells (CD3-/CD16+56+), and B-lymphocyte. These data are suggested that cell-mediated immunity plays a role in later stages of the diseases.

IFN-γ and IL-12 production from human whole blood cultures.Clinical hallmarks of severe leptospirosis can resemble Gram-negative sepsis, with multiorgan failure, refractory hypotension, and death.However, the pathogenic mechanisms from either the host or the pathogen side that results in the clinical manifestations of human leptospirosis remains unclear.Naturally acquired immunity that protects against reinfection by Leptospira does occur and has been shown to be serovar-specific in animal models.It has been assumed that naturally acquired immunity is humorally mediated.It has been proposed that immunity is linked to antibodies directed against oligosaccharides of serovarspecific leptospiral LPS, and that leptospiral LPS stimulation of the innate immune system via a Toll-like receptor 2 (TLR2)-dependent mechanism may be important in leptospirosis.There is also evidence that antibodies specific to Leptospira membrane-associated proteins may play a role in host defense.The recent observation that high grade bacteremia (10 1 -10 6 /mL) in leptospirosis can occur in the presence of moderate or high titer anti-leptospiral agglutinating antibodies makes it plausible that mechanisms other than anti-LPS antibodies play a role in naturally acquired protective immunity (2).The role of cell-mediated immunity in host defense to Leptospira remains poorly understood in both animal models and human disease (2,4,5).
The aim of this study is analysis of flow cytometric investigations in cases with leptospirosis.

DISCUSSION:
The leptospiral invasion and its dissemination turn on intensive immune mechanisms.It is known that the course of the disease is in two phases -acute (septicemic) and immune (followed septicemic) (3).The early immunogenesis in leptospirosis is humoral -IgM antibodies have been produced followed by longer persisting IgG antibodies.Complement IgG antibodies participate in stimulating of bactericidal activity of the macrophages.The host participates with non specific inflammatory mechanisms and with cell-mediated immunity which plays a role in later stages of the diseases (2).This correlates with our observations.At the summarize of the results from flow cytometric immunophenotypization of six lymphocyte populations and subpopulations a prevalent tendency has been found for decreasing of the number of

CONCLUSION:
The cell-mediated immunity plays an important role in the pathogenesis of leptospirosis.An investigation by flow cytometry might be facilitating the registration of fine abnormalities in cell subsets.Further researches are needed for elucidation in this respect.
total T-lymphocytes, T-helpers, T-suppressors, T-helpers/ T-suppressors index; increasing of the number of the activated T-lymphocytes, subpopulation of NK cells (CD3-/CD16+56+), and B-lymphocyte.These data have been correlated with the observations of Mel'nik GV, et al. (1995) and especially with results of Yamashiro-Kanashiro EH, et al. (1991) which by immunofluorescence observed declining in the CD3+ and CD4+ cell subsets in patients with and without acute renal failure (4, 5).In the literature we had not found data about flow cytometric investigations of lymphocyte populations and subpopulations in leptospirosis.

Table 1 .
Investigations of lymphocyte subpopulations by flowcytometry a. N -reference value b. <N -below reference value c. >N -above reference value d. n -number of cases