A biometrical view on normal values of CD4 and CD8 lymphocyte counts in peripheral blood

The fermentable fiber content of the diet alters the function and composition of canine gut associated lymphoid tissue

The ingestion of plant fibers and their susceptibility to microbial fermentation in the large bowel modulate intestinal morphology but little is known about effects on the gut associated lymphoid tissue (GALT). The aim of the present study was to determine the effect of consuming diets containing different levels of fermentability fiber on immune function. Sixteen adult mongrel dogs (23 +/- 2 kg) were fed (14 days) in a randomized cross over design two isoenergetic isonitrogenous diets containing 8.3 g/kg non-fermentable or 8.7 g/kg fermentable fibers. Lymphocytes were isolated from blood prior to starting the study and at the end of each diet period. At study completion, lymphocytes were isolated from the gut associated lymphoid tissue (GALT) of the small intestine for characterization by immunofluorescence and to determine their ability to respond to mitogenic stimulation. Feeding high fermentable fibers increased (P < 0.05) the CD4/CD8 ratio and decreased (P < 0.05) the proportion of B cells in peripheral blood without changing natural killer cell activity or the response to mitogens. Mesenteric lymph node cells from dogs fed the low then high fermentable fiber diet contained a higher (P < 0.05) proportion of CD4+ cells and a higher (P < 0.05) response to mitogens. Intraepithelial, Peyer's patches and lamina propria cells contained a greater (P < 0.05) proportion of CD8+ cells when dogs were fed a low fermentable fiber diet followed by a high fermentable fiber diet. T cell mitogen responses in vitro were higher for intraepithelial but lower for Peyer's patches and lamina propria cells from dogs who were fed the low fermentable fiber diet followed by the high fermentable fiber diet (P < 0.05). In conclusion, the fermentable fiber content of the diet had very little effect on the type and function of immune cells in peripheral blood. However, feeding dogs a high fermentable fiber diet for 2 weeks (after 2 weeks of consuming a low fermentable fiber diet) altered the T-cell composition of GALT and produced a higher mitogen response in the predominantly T cell tissues and a lower response in areas involved in B cell functions. In conclusion, the level of fermentable fiber in the diet appears to alter GALT properties. Further studies are required to determine the direct contribution of a high or low fiber diet to these changes and the physiological implications to the health of the animal.

CD8+ cell-mediated immune responses: relation to disease resistance and susceptibility in lentivirus-infected primates

Immune responses mediated by CD8+ lymphocytes have been correlated with protection from HIV infection and disease progression in humans and nonhuman primates. The CD8+ cell population is heterogeneous in terms of biological function and phenotype. We have undertaken a review of the current state of knowledge of subtypes of CD8+ cells and their role in immune responses directed to HIV and related primate lentiviruses. Differences in the pathogenesis of lentivirus infections in various primate hosts were examined and the possible roles of the various subpopulations of CD8+ lymphocytes in the resistance and/or susceptibility to lentivirus-related disease were compared.

Functional and phenotypic analysis of in vitro stimulated canine peripheral blood mononuclear cells

The inter-species cross-reactivity of cytokine bioassays for interleukin-2 (IL2) and interleukin-6 (IL6) was investigated in the canine species. The kinetics of normal canine peripheral blood mononuclear cells (PBMC) stimulated with pokeweed mitogen (PWM), were analyzed in terms of cytokine release and responsiveness to cytokine stimulation, in conjunction with determination of cell proliferation, de novo antibody synthesis and cell surface phenotype. PBMC were stimulated with PWM at the beginning of the culture and human recombinant IL2 (rIL2) was added 3-4 days post stimulation (d.p.s.). Mitogenically stimulated cells proliferated and synthesized antibody in a linear fashion up to 6 d.p.s. Resting PBMC had a mean CD4+/CD8+ ratio of 1.7:1; whereas cells stimulated with PWM were predominantly of CD8 phenotype at 7 d.p.s.. Three days after addition of IL2, stimulated cells were predominantly of the Thy+, sIg-, CD4+, CD8- phenotype, with an increase in the CD4+/CD8+ ratio. The magnitude of de novo antibody synthesis was lower in rIL2-supplemented cultures than in cultures stimulated only with PWM, and suggested a negative relationship between de novo antibody synthesis and proliferative responses of the same cultures. Supernatants from mitogen-stimulated cultures induced proliferation of mouse IL2- and IL6-dependent cell lines. Antibodies reactive with human IL2 or IL6 inhibited these responses. IL2-like activity in PWM-stimulated culture peaked by 2 d.p.s. and decreased thereafter. IL6-like activity peaked later (4-6 d.p.s.).

Clinical and immunological follow-up of previously hospitalized HIV-2 seropositive patients in Bissau, Guinea-Bissau

A follow-up study was done in Bissau on 113 HIV-2 seropositive patients and 97 HIV-2 seronegative patients 3-15 months after hospitalization. Follow-up totalled 63.5 person years for seropositive patients and 62 for seronegative patients. The mortality during the follow-up period was 43.3% among the seropositive patients (rate 72/100 person years; p.y.) and 25.8% among the seronegative patients (40/100 p. y.). Among 25 HIV-2 associated AIDS cases the mortality was 80% (rate 117/100 p. y.). The median survival time for the AIDS patients was 8 months. Among 48 HIV-2 seropositive patients who lacked signs or symptoms included in the WHO case definition for AIDS at the time of hospitalization 6 patients (12.5%) developed AIDS related symptoms (ARS) during altogether 31.5 person years of follow-up (rate 19/100 p. y.). Tuberculin anergy was demonstrated in 83.3% (15/18) of HIV-2 seropositive patients with AIDS or ARS, in 14.3% (6/42) of seropositive patients without HIV-related symptoms and in 6.9% (5/72) of seronegative patients. A low CD4 T-lymphocyte count in combination with a low CD4/CD8 T-cell ratio was found significantly more often in HIV-2 seropositive patients with AIDS or ARS (62.5%, 10/16) than in HIV-2 seropositive patients without HIV associated symptoms (6.9%, 2/29) or in seronegative patients (2.7%, 1/37). Thus the mortality among recently hospitalized HIV-2 seropositive patients was high and a high proportion of seropositive patients with HIV-related symptoms had evidence of immunodeficiency.