Biomedical subjects

R O Garcia

Publications and source records attributed to R O Garcia.

4 recordsLinked to original sources

PubMed1989

Sex difference in the CD4 + CD45R+ T lymphocytes in normal individuals and its selective decrease in women with idiopathic thrombocytopenic purpura.

Chronic idiopathic thrombocytopenic purpura (ITP) is a well-defined autoimmune hematologic disorder. It is more common in women than men. We have shown that patients with active disease have abnormal T cell subsets which are more perturbed in women than in men and functional abnormalities that are confined to the T lymphocytes. In the current study, the anti-2H4 (CD45R) monoclonal antibody was used to divide the CD4 subset into their CD4+ CD45R+ and CD4+ CD45R- T lymphocytes. The subpopulations were measured in the peripheral blood of 26 women and 15 men with active ITP, 16 women and 8 men with disease in remission, and 33 normal healthy women and men. Normal women had increased percentages (P less than 0.0001) and numbers (P less than 0.005) of the CD4+ CD45R+ lymphocytes compared to normal men. Women with active disease had reduced percentages and numbers of CD4+ CD45R+ lymphocytes compared to normal women (P less than 0.0001) and women with disease in remission (P less than 0.001). Those women with decreased CD4+ CD45R+ lymphocytes had a significantly depressed lymphocyte response to polyclonal T cell mitogens. In contrast, men with active disease had neither such phenotypic changes nor functional correlations. The percentages and numbers of CD4+ CD45R- lymphocytes were not changed in either sex with active disease. In conclusion, women, but not men, with active ITP appear to possess a reduced subpopulation of CD4+ CD45R+ T lymphocytes.

Antibodies, Monoclonal↗

PubMed1989

Very low dose danazol in idiopathic thrombocytopenic purpura and its role as an immune modulator.

Danazol, an attenuated androgen, has been used successfully at its conventional dose (400-800 mg/day) in the treatment of idiopathic thrombocytopenic purpura (ITP). To minimize side effects, the authors tried a very low dose (50 mg/day) regimen which has not been used in any other disease and observed its efficacy in ITP. Fifteen patients were given this dosage of danazol. Its effects on T-cell subsets, B cells, and blastogenic response to pokeweed mitogen (PWM) and staphylococcus aureus (Staph A) were studied before and during therapy. The percentage of CD3 and the percentage and numbers of CD4 were significantly increased during therapy. Responses to PWM, a T-cell dependent B cell mitogen, were also significantly elevated during therapy. However, no change in the percentage of B (CD19) lymphocytes and response to Staph A, a polyclonal B cell mitogen, were noted. There were seven excellent-good and eight fair-poor responses in platelet counts. The excellent-good responders were found to have a more stable CD4 subset between before and during therapy compared to the fair-poor responders (p less than 0.05, Fisher's exact test). Very low dose danazol regimen, therefore, produced a significant increase in the CD4 without affecting the B cells. However, the excellent-good responder patients showed no significant increase in the CD4 lymphocytes.

Adult↗

PubMed1988

Depressed functional and phenotypic properties of T but not B lymphocytes in idiopathic thrombocytopenic purpura.

Chronic idiopathic thrombocytopenic purpura (ITP) is an autoimmune disorder in which the abnormality in cellular immunity has remained only vaguely defined. Previously we have shown that patients with ITP in its active phase have abnormal T cell subsets. We then examined the phenotypes of T and B lymphocytes in an additional 28 patients with ITP and 32 age- and sex-matched normal controls and compared the lymphocytes' capacity to respond to polyclonal T, T cell-dependent B, and B cell mitogens. Blastogenesis to optimal (5.0 micrograms/mL) and suboptimal (0.5 microgram/mL) concentrations of the polyclonal T cell mitogens were markedly depressed in patients compared with normal controls (P less than .0005). Similarly, a severe depression in response was noted with the polyclonal T cell-dependent B cell mitogen (P less than .000001). No difference was seen, however, with the polyclonal B cell mitogen. The proportions of pan-T and T helper/inducer lymphocytes were significantly depressed (P less than .005 and P less than .000005 respectively), and the T suppressor/cytotoxic lymphocytes increased (P less than .02) in patients relative to controls. But there was no difference in the proportion of B lymphocytes or in their functional response. The abnormal cellular immunity appears to be due to a defect in the T lymphocyte population without involvement of the B lymphocytes.

Adult↗

PubMed1987

Low-dose danazol therapy in idiopathic thrombocytopenic purpura.

Although danazol is effective in the treatment of idiopathic thrombocytopenic purpura, its long-term safety and optimal dosage are not well established. We compared low (50 mg/d) and conventional (400 to 800 mg/d) dosages in 24 patients. Thirteen patients received the low dose 1 to 24 months after conventional doses had been discontinued (group 1). Five patients received low doses immediately after the conventional doses (group 2). Six patients were treated with low doses from the outset (group 3). In group 1, similar responses to either dose were seen in 9 patients, whereas there were better responses to conventional doses in 3 and to the lower dose in 1. All patients in group 2 maintained remissions with low doses. There were two excellent-good responses, one fair, and three poor responses in group 3. Side effects were generally less frequent and severe with the low doses. Low-dose danazol is better tolerated but took longer to obtain remissions, and is useful for maintenance therapy in the management of idiopathic thrombocytopenic purpura.

Adolescent↗