Usha Datta

Immune responses in patients with HIV infection after vaccination with recombinant Hepatitis B virus vaccine

BackgroundPatients with HIV infection are at risk of co-infection with HBV, as the routes of transmission are shared and thus immunization with HBV vaccine could be protective in them. The aim of the present study was to assess the efficacy of recombinant vaccine in treatment-naive HIV positive patients and healthy controls, and to dissect out differences if any, in different limbs of immune response.MethodsForty HIV positive patients and 20 HIV negative controls, negative for HBsAg, HBsAbs and HBcAbs were vaccinated with three doses of 40μg and 20μg of vaccine respectively. Patients were divided into high CD4 and low CD4 group based on CD4+ lymphocytes of 200 and < 200/mm3 respectively. Group II consisted of healthy controls. Detection of phenotypic markers was done by flowcytometry. Cytokine estimation was done by sandwich ELISA. HBsAbs were estimated in serum by ELISA.ResultsAfter vaccination, CD4+, CD8+ and CD3+ cells increased significantly in all the groups. There was no increase in NK cell activity in patients with high CD4+ lymphocytes and only a marginal increase in patients with low CD4+ lymphocytes (170 to 293/mm3) whereas a marked increase was observed in controls (252 to 490/mm3). After vaccination, although an increase in memory cells was observed in HIV positive patients, yet HBsAb levels were significantly lower than controls (P < 0.05) indicating a functional defect of memory cells in HIV/AIDS patients. Basal IFN-γ levels were also significantly lower in HIV/AIDS patients (P < 0.01). Although the levels increased after vaccination, the peak level remained lower than in controls. HBsAb titers were much lower in HIV positive patients compared to controls. (High CD4+ group: 8834 mIU/ml, low CD4+ group: 462 mIU/ml Vs. Controls: 16,906 mIU/ml). IL-4 and IL-10 were low in patients.ConclusionDespite a double dose in patients, IL-4 and IL-10, which regulate antibody response, were also lower in patients, and this together with low CD4+ counts and lack of T help, accounted for low HBsAb levels. Vaccination in patients with CD4+ lymphocytes < 50/mm3 was ineffective. Thus early immunization is advocated in all HIV positive patients at a stage when they are still capable of mounting an adequate immune response

Immune functions in splenectomized thalassaemic children

A prospective study to assess the immune functions in splenectomized thalassaemic children. Children were those registered in the Thalassemia major. There were 10 splenectomized children (Group 1), 10 nonsplenectomized children and 6 age-matched control (Group 3). All children were shown to be HIV seronegative. The mean concentrations of serum IgG and IgA were higher in Group 1 as compared to Groups 2 and 3 but the differences were not statistically significant. Nitroblue tetrazolium (NBT) dye reduction by stimulated polymorphonuclear leukocytes was normal in both study and control groups and the differences were not statistically significant. However, NBT reduction in the unstimulated state was much higher in Group 2 as compared to Groups 1 and 3. Phytohaemagglutinin induced mitogen proliferation was normal in all 3 groups. Children in Group 1 not only had a significantly higher absolute lymphocyte count but also had a lower CD4JCD8 ratio as compared to Groups 2 and 3. Splenectomy does appear to alter the immune status of thalassemic children but the exact mechanism by which this occurence is not clear.

Cellular and serological markers of disease activity in Indian patients with HIV / AIDS.

There has been an exponential rise of HIV positive patients as observed at the surveillance center of Nehru Hospital. Most patients are poor and cannot afford repeated viral load assays. Therefore, there is a need to identify cost effective and reliable surrogate markers of disease activity. In the present study absolute number of CD4 cells, beta2 micro-globulin, circulating nucleosomes were studied in 30 patients of AIDS, 30 seropositives and 30 healthy controls. In addition viral load, P-24 assay, and TNFR-II assays were done in seropositive and AIDS patients. The mean CD4 cells in patients with AIDS were 69.66 +/- 68.25 mm3 while in seropositives values was 370 +/- 201.29 mm3. The mean CD4 cells in healthy controls were however 690 +/- 198 mm3. The differences in all the groups were highly significant (p<0.001). The mean CD4 values in Indians are significantly lower than reported from the west. The lower number of CD4 cells in healthy population is interpreted to be due to immune activation. The CD8 cell number in controls was 650 +/- 207 mm3 this figure is also higher than that observed in the west. P-24 assay failed to delineate between seropositives and patients with AIDS. Although, beta2 microglobulin levels were significantly higher in AIDS than in seropositives and higher in seropositives than in controls yet with the best possible cut off, it had a sensitivity of only 70% in delineating the two conditions. The correlation between CD4 cells and viral load was more significant when the CD4 cells were below 200 mm3. Five out of 30 patients with a CD4 of 300-600 mm3 had a viral load of over 1 x 10(5) cop/ml. The difference in TNF R-II levels between seropositives and AIDS was however more impressive. With a cut off of 550 pg/ml it had a sensitivity of 95% in delineating HIV from AIDS. It is concluded that a combination of absolute number of CD4 cells and TNF R-II assay along with clinical evaluation may be used to monitor therapy in resource poor countries where frequent viral load assay is unaffordable.

Importance of Bone Marrow Culture for Diagnosis of Kala Azar

Kala azar was diagnosed in 45 clinically suspected cases following bone marrow smear examination and in vitro culture of the aspirate. Bone marrow aspiration smear examination revealed amastigotes in 27 cases (60%). In vitro culture of the aspirate demonstrated leishmania parasites in 44 cases (97.8%). A total of 18 cases (40%) were negative for amastigotes in smear examinations but parasites could be demonstrated by culturing the same aspirates. The in vitro culture of bone marrow is necessary to diagnose Kala azar and is strongly recommended to be performed along with the bone marrow smear examination.

Low sensitivity of counter-current immuno- electrophoresis for serodiagnosis of typhoid fever

Counter-current immuno-electrophoresis was evaluated as a diagnostic test for the serodiagnosis of typhoid fever with somatic (O), flagellar (H) and capsular polysaccharide (Vi) antigens of Salmonella typhi on the sera of patients who were blood culture positive (confirmed typhoid cases) or had high Widal agglutination titres, > or = 320, (presumptive typhoid cases). Of the 37 sera from confirmed cases, 30% showed positivity with O antigen, 24% with H antigens and 51% with Vi antigen. In patients with a presumptive diagnosis, 45% were positive for O antibody, 27% for flagellar antibody and 52% for Vi antibody. When all three antigens were combined the reactivity to any of the antigens was found to be 59% in confirmed typhoid cases, 79% in presumptive typhoid cases and 93% in patients who were simultaneously positive by blood culture and Widal agglutination. However, none of the sera from 45 controls gave a positive precipitation reaction with any of the antigens. It is concluded that counter-current immuno-electrophoresis is a rapid test with low sensitivity and high specificity with Vi antigen, a panel of antigens being most effective, and is, therefore, recommended for rapid diagnosis of typhoid fever.