Table 4.
Association of different anti-Tat antibody isotypes with CD4+ T cell count and viral load
| Associationa of duration of HIV infection and anti-Tat antibody isotype with CD4+ T cell counts (n = 88) | |||||||||
| Univariate | Multivariate | ||||||||
| Covariate | Stratum | n | Mean CD4+ T cells count (cells/μL) | IRR | 95 % conf.int. | p-value | IRR | 95 % conf.int. | p-value |
| HIV infection (years) | >3 | 69 | 403 | 1 | – | – | 1 | – | – |
| ≤3 | 19 | 501 | 1.24 | (0.98 to 1.58) | 0.079 | 1.10 | (0.86 to 1.41) | 0.443 | |
| IgG | neg. | 48 | 431 | 1 | – | – | 1 | – | – |
| pos. | 40 | 415 | 0.96 | (0.76 to 1.22) | 0.764 | 0.97 | (0.77 to 1.21) | 0.761 | |
| IgM | neg. | 43 | 353 | 1 | – | – | 1 | – | – |
| pos. | 45 | 491 | 1.39 | (1.10 to 1.76) | 0.007 | 1.34 | (1.05 to 1.71) | 0.019 | |
| IgA | neg. | 73 | 448 | 1 | – | – | 1 | – | – |
| pos. | 15 | 306 | 0.68 | (0.51 to 0.91) | 0.010 | 0.73 | (0.55 to 0.95) | 0.020 | |
| Associationa of duration of HIV infection and anti-Tat antibody isotype with Log10 VL (n = 83) | |||||||||
| Univariate | Multivariate | ||||||||
| Covariate | Stratum | n | Mean viral load (Log10 copies/ml) | IRR | 95 % conf.int. | p- value | IRR | 95 % conf.int. | p-value |
| HIV infection (years) | >3 | 65 | 4.68 | 1 | – | – | 1 | – | – |
| ≤3 | 18 | 4.26 | 0.91 | (0.79 to 1.05) | 0.203 | 0.96 | (0.83 to 1.10) | 0.553 | |
| IgG | neg. | 45 | 4.47 | 1 | – | – | 1 | – | – |
| pos. | 38 | 4.74 | 1.06 | (0.96 to 1.16) | 0.230 | 1.05 | (0.96 to 1.15) | 0.284 | |
| IgM | neg. | 40 | 4.84 | 1 | – | – | 1 | – | – |
| pos. | 43 | 4.36 | 0.90 | (0.82 to 0.99) | 0.027 | 0.92 | (0.85 to 0.99) | 0.037 | |
| IgA | neg. | 68 | 4.46 | 1 | – | – | 1 | – | – |
| pos. | 15 | 5.20 | 1.17 | (1.08 to 1.26) | <0.001 | 1.13 | (1.06 to 1.21) | <0.001 | |
IRR incidence rate ratio
aPoisson regression with robust variance estimates was used to examine the association of Tat antibody isotypes with CD4+ T cell count and viral load. The table shows that the duration of HIV infection and anti-Tat IgG positivity had no significant influence on both parameters, whereas the presence of anti-Tat IgM and IgA were significantly associated with CD4+ T cell count and viral load. Anti-Tat IgM positivity was associated with higher CD4+ T cell counts and lower viral loads, whereas anti-Tat IgA positivity showed the opposite pattern. The fact that multivariate IRRs and p-values for both parameters are fairly similar to the univariate estimates suggest that these associations are independent of each other