Lymphocyte activation and cytokine production in autoimmune hemolytic anaemia (AIHA)

We studied 16 patients affected by autoimmune hemolytic anaemia (AIHA), both idiopathic and associated with other diseases (B and T lymphoma, B hepatitis, gastric carcinoma, systemic lupus erythematosus) or a-methyldopa therapy, in order to value T- and B-cell activation. We determined the count of T- and B-cell subsets in peripheral blood, the proliferative response of peripheral blood lymphocytes (PBL) to phytohemagglutinin (PHA) and to pokeweed mitogen (PWM), the percentage of CD25(+) cells in culture and interleukin (IL)-1 alpha, IL-2, IL-4, tumor necrosis factor (TNF)a and soluble IL-2 receptor (sIL-2R) levels in sera and in culture. Except for an increase in CD4(+) and CD8(+) T cell number in a case of AIHA associated with a T lymphoma and an increase in the percentage of CD5(+) and PCA1(+) B cells in two cases of AIHA associated with B lymphoma and with SLE, no further data showed a relationship with the disease possibly associated with AIHA, so both idiopathic and secondary AIHA cases mere analyzed together. CD4(+) T cells were reduced in number in 9 cases, while CD8(+) T cells were reduced in 6 cases. The percentage of CD5(+) B cells was increased in 5 cases. The percentage of PCA1(+) cells was increased in all cases (mean+/-sd: 18+/-22 vs 0,2+/-1 in controls). The average PBL proliferative response to PHA was reduced (S.I. 71 +/- 55 vs 138 +/- 45 in controls) as well as that to PWM (S.I. 27+/-21 vs 75+/-24 in controls), despite IL-2 high levels, in all cases, in both sera (mean+/-sd: 648+/-351 pg/ml vs 16+/-4 pg/ml in controls) and culture supernatants (mean+/-sd: 1045+/-677 pg/ml vs 195+/-51 pg/ml in controls). In PHA stimulated cultures the percentage of CD25(+) cells was reduced (mean+/-sd: 37+/-18 vs 63+/-14 in controls), sIL-2R levels were like controls in 7 cases. In sera sIL-2R levels mere increased in all cases (mean+/-sd: 1256+/-465 U/ml vs 256+/-114 U/ml in controls), IL-1 alpha was increased in all cases too, while IL-4 levels were increased only in 7 cases. Linear regression analysis generally showed a low relationship between S.I. and IL-2, IL-4 and sIL-2R levels in supernatants of PHA stimulated culture as well as between S.I. and the percentage of CD25(+) cells. Taken together these data suggest a state of B- and T-cell hyperactivation in AIHA. The lon PBL proliferative response in vitro, explained in previous studies as a temporary functional exhaustion, might be itself a sign of the complete lymphocyte activation occurring in vivo in AIHA.