CD86 and agammaglobulinemia: Due to the changes in the percentage of selected immune cells observed in the immunophenotype, in the next stage of the research, we conducted an assessment of PD-1/PD-L1, CTLA-4/CD86, and CD200R/CD200 in selected subpopulations of T and B lymphocytes in patients with antibody deficiencies with near-normal immunoglobulin levels or hyperimmunoglobulinemia in relation to healthy volunteers.